Charles,
Seems I'm a little late in this discussion, but welcome to the mild insanity of MGA restoration. From your messages I know you have far more experience than the average Joe who takes on a full restoration project. The prime ingredients in final success are a passion and determination to see it through without too much delay. If you just keep working on it regularly it will eventually be finished. Anything you don't know about this specific model you can learn along the way.
Others have already turned you on to most of the right books and web sites. I don't see prior mention of a couple of other useful MGA forums. You should at least check into
the UK "green board" MGA BBS here: http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs
and the MG Experience MGA forum here: http://www.mgexperience.net/phorum/list.php?
Body repair and restoration will be about 70% of the project labor, but maybe only 20% of the project cost. It is mostly grunt work and not so much cost in materials. Frame and running gear rebuild is almost trivial by comparison, as long as you leave the engine and gearbox under the workbench until body and chassis are finished. On that path you can also delay any decision on drive train mods until near the end. The only good reason (other than personal gratification) to set an engine in the chassis early on is if you know that it will be something that will not bolt into the original space and mountings. Once the restoration work is done (everything clean and painted), the reassembly work goes relatively fast. If you plan it right you don't need to spend money on engine and trim parts until about the day the body will be mated to the chassis, and then you get to write the big checks for the stuff you need to make it complete.
There is (or at least was) an MG club in Oklahoma City. Their web site link is currently broken, but you can find older copies of the web site here: http://web.archive.org/web/*/http://www.mgcarclubok.org
There are also some phone numbers found there (if they still work).
MG Car Club of Oklahoma
http://www.mgcarclubok.org (currently broken link)
1021 NW 67th, Oklahoma City, OK 73116
Don Perry, Editor (405) 842-7023
As fond as I am of NAMGAR, I don't suppose that membership would be of much help with your restoration. They publish a pretty magazine style newsletter six issues per year, and they stage a GT (Get Together) somewhere in North America once a year, mostly of interest for those with running cars. There used to be some technical information on their web site, but that was removed when they published a tech book for sale. Their most important contribution to your project might be a target date for the first GT you may be able to attend with your finished car.
Others have already mentioned my web site http://MGAguru.com, with over 1400 web pages of tech information of MGA. Perhaps the more important part of that web site is the always open e-mail link. If you can stump me with an MGA question that is not already covered on my web site, it may lead to some research and another tech page.
Chemical stripping and electro etching is an easy way to get to bare metal and also remove rust, but it is getting quite expensive these days with all the EPA regulations and enviro-taxes. Media blasting is very quick to bare metal, likely cheaper than professional chemical stripping, as long as you keep the blaster away from the aluminum panels. I have found that most of the original rust goes away when you cut out cancered panels and weld in new metal. If you do the repair work before having it stripped, then the stripping will be easiest and least expensive, and it cleans up your metal repairs at the same time.
I recently removed all paint form the outer body surface of my MGA with a 4-inch angle grinder and sanding flap discs (using a slower large disc sander for the alloy panels). My car was not a total rust bucket, mostly only needing the body sill replacement, as it had previously been painted all underneath with prior work. Restoration of a virgin car will almost certainly require stripping everything inside the body that can only be done with chemicals or blasting.
The MGA body in good condition is quite a ridged structure that can be lifted and handled without need of any internal bracing. Problem is, most "never restored" MGAs will have badly rusted body sills, many so bad that the body would come off in pieces. If the frame is still structurally solid enough to hold the body in alignment, then the best approach is to do all of the internal body repairs while it is still on the frame. Then you can lift it off to do underbody cleanup and painting.
If you do remove the body first, and it is not structurally sound, then you will most likely need to put it back on the frame as a jig for realignment. The MOST IMPORTANT KEY to making the MGA body fit together and function is to start in the middle and build the body around the doors. Make hinges and latches work first, then fit up the body sills and rocker panels, and finish by aligning the fenders for nice panel gaps.
As to making your own body panels, .... Note that all of the internal lower body parts are flat stock with bends, so generally easy to hand form, and small flanges are pretty easy. If you make your own they will be formed to fit, so no problem with market parts that may not fit the first time.
The only lower internal parts that gave me a slow time were the long box panels, as the two long bends are somewhat tough and slow to hammer form. Even if you have access to a large press brake there is still come hand forming here as a couple of the bends have varying angle over the length of the part. I spent two days figuring out how and hammering up the first one, and one day on the second one. If I had to do it again I might make two in one day, but it is still not an economical proposition unless your time is very cheap or free. I went through the exercise primarily to show that it could be done if you were on a shoestring budget with more time than money. Those pieces are under $100 each in the commercial market.
I have not made any extensive amount of outer contour body panels, only a few small patch pieces. For larger contour panels you likely need an English roller and a flange roller and some experience to pull it off. The cost of those tools and the learning curve are not viable for a first or single restoration. I bought rocker panels, and I did a little patching in the lower fenders, but otherwise all of my outer panels were generally reusable.
Beware of a large variety of ill fitting body panels on the market. Ask questions about specific pieces, try to find the good ones to buy and avoid the ill fitting ones as much as possible. You may find the hard way that making your own panel is no more time consuming than fitting up some of the bad commercial parts.
Original MGA body sheet metal is mostly 18 Ga (0,048") inside and out, two pounds per square foot, thick enough for generally easy welding. MGA frame metal is mostly 14 Ga (0.075") flat stock and round tubing, a little tougher to bend but easier to weld. Nationality of the steel may be irrelevant these days, as long as it is thick enough. I didn't bother to ask what country my flat sheet steel stock came from, but I am well aware that foreign mills have mostly put the American makers out of business some time ago.
On your torched out firewall, exactly which panel is it? The sheet metal panel above the tunnel and below the frame goalpost is a removable piece screwed to the front of the goalpost. Good used panels pop up on eBay fairly often. If someone torched the goalpost cross tube, then you will have some welding repair to do.
Good luck, and keep asking questions as required.
Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com