newbie,
The first thing you need to do is sit down and think about the real cost of doing this job. Big Healey parts prices are high. This is because the cars are less numerous than MGs, TRs, and such. Just to show an example, I usually charge in the area of six thousand dollars to remove, overhaul, refinish, reaccessory, reinstall, and retune an MGB engine. This climbs to over ten thousand with a Healey six. The rest of the car follows suit, and if you have some of the typical structural rust issues that you really don't see at first, you are in for a slog. I don't really mean to discourage you, though, just to prepare you. Get a catalog and a calculator and "bracket" everything you will have to do with lower prices for the smallest number of new parts and services, and worst case prices for the same. Now, average the two and move upward by about twelve percent. You will spend this much EASILY. Remember, these are very desirable cars, and thus, if yours is to be one of the truly valuable of the last most valuable Big Healeys, it has to be done to a tee. On the other hand, if you just want a fun driver, you can certainly take shortcuts, and there's NO SHAME in that. In fact, I tend to drive classic sports cars in excellent mechanical condition with compromised exteriors that I park wherever I fell like parking and drive without fear of chips.
The engine will need total overhaul by someone who understands these engines and their kinks. I would try to get this car for less than the asking price for this and other reasons. These are not good times to be selling cars in need of total restoration. Let the seller know that you are well aware that the cost of doing the work is quite high, and that perhaps that's why HE isn't doing it. This will deflect with verbal jujitsu his claim that when you get it done it will be SO valuable. Be aware, that no car restored correctly will be worth at completion what it cost to get it that way. Never.
There a LOT of details to cover here, and since the car does not run, you must assume the worst. Such as: does the overdrive function? Rather expensive to repair or replace, the overdrive is not an easily serviced unit at home. There are specialists. The list goes on. These are detailed cars, though elegant and powerful.
If you really want one, look for one that's already running and has few problems; problems you can detect at purchase. It will be cheaper in the long run. On the other hand, if what you really want is the committed relationship to a project that is restoration, welcome to the club!!
Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon