you will get many opinions on this. some love the DGV, others claim the SUs are the proper carb for an MG. Personnally I don't care what's "proper" as much as what I think works better.
I think either would be a little better than the Stromberg, but I've heard that a properly set up and maintained Stromberg is actually pretty good. Most of them are ignored and they carbon up, cause the cat to glow red and cause other problems. I've never had a RB car myself, so can't be first-hand on this.
I tried a DGV on my 73 because the original HIF were in need of rebuilding. I tried it for several years, with an engine rebuild in the middle. Then I replaced it with a set of proper SUs and the difference I felt was night and day.
The DGV I bought from a well known (not Moss) vendor was supposed to be jetted specifically for the B. I don't think so! It got 15-17 mpg. I thought about rejetting it because Webers do not have any adjustments beyond idle mixture. To do this I would have had to obtain a set of 3-4-5-6 different pieces with different values of each -- I had the SUs repaired. The difference was very pleasing.
There are folks who have had the opposite experience...they love their Weber. I loved the ease of starting (pump it a couple times and start), I loved the progressive hit when the secondary cut in.
If I had gotten it adapted properly for my engine (or, perhaps, if I tried it on a different car), I probably would have loved it too. I have seen several internet postings suggesting the properly revised jetting so maybe the process was not going to be as awkward as I imagined at the time.
I'd be happy to get $125 for it, with manifold, extra throttle cable, and modified cable mount which allows full throttle (the kit as I got it would not even permit that!)
Rather than spend the catalog or discounted price for a new DGV I would suggest getting a set of SUs from Jimmy Hilton in Carroll Texas (jimmy@batterypowered.com).
The 76 suffers from more than the Stromberg -- if the 76 is comparable to the 78-79: the cam is less agressive and the ignition advance curve is not very good. But either the dgv or a pair of SUs would perk it up a bit. So would a properly curved distributor (contact Jeff@advanceddistributors.com) regardless of the carb. Either would allow (indeed, require) a different exhaust manifold and down pipe.
The stock cast iron manifold from the pre-Stromberg cars is as good a flowing "header" as 90% of the headers you'll find for use on the street with unmodified heads and stock-type cam.
There are two exhaust manifolds that differ by the thickness of the bolt-up flange. One thickness matches up with the HS4 SU intake manifold (9/16" thiock flange) and the other is later, matching the HIF (72-up) SU intake manifold. The Canon manifold that (usually) comes with the DGV setup uses the 9/16" flange, so a 71-earlier exhaust manifold would be an easier match (you won't have to tinker with shimming). You can put any exhaust system on in back of the stock manifold that you might want. I think trying for a header on your car is a waste of money until you are able to rebuild the engine with a better cam, higher compression, and possibly head work.
Oh...you had better check the laws in your state. In California doing something like this won't let you pass the smog inspection you are required (with a 76) to pass. <G>
Old Fart
71 GT project
73 Roadster runner