Buy the nicest body you can afford. Good bodywork isn't cheap & cheap bodywork isnt good.
Yes I’ve worked with plenty of engineers like that too. Fortunately I’m in the 50% of engineers who like to get their hands dirty. Grew up on a farm, spent plenty of time around tractors. I’ve fixed/upgraded/remodeled just about everything in 3 different houses. I’m a gunsmith, blacksmith, luthier, electrician and electronics tech. So while I don’t know cars/engines much… I can learn. I have no doubts.Here's my two cents (and you're welcome to put the two cents towards the purchase of your car) and please don't take this the wrong way: I'm not an engineer but I work with plenty of them. If you are a mechanical engineer with zero mechanic experience, it will drive you bonkers to try to rebuild an old car. Most engineers I know see the world in black and white - "the drawing says part A attaches to part B". In the real world, part A should attach to part B easily, but it never does. You'll have to figure out how to get it to attach. As my wife says, " Why do you work on that old car when you get so frustrated every time?" And my answer always is "Because I love to!" There is nothing more satisfying that when working on a car, you have to run back and forth to the parts house because they gave you the wrong part, then you find out you don't have the right tool so you have to either find someone to borrow one from or buy a new one, you bust a few knuckles trying to put it on, only to have it leak so you have to take it back off and modify it, and then several hours (or days) after what should have take a few minutes, you get to hear that engine fire up.
My suggestion - buy a running car. Drive it so you can enjoy it now. Read everything you can about cars so you can learn about how cars work. Figure out what you really want to do to it, and how much you can realistically spend, then slowly do what you have planned to it and make it your car. Being able to drive it will keep you interested. If you buy a non-running car that may take several years to get running you could easily lose interest or get tired of putting money in it without enjoying it. And if you sell it before it's finished you won't get near what you have invested in it. Plus having a running car may get your wife and kids interested in helping! My wife is definitely not a car person, but she loves my Chevelle. When we're out riding in it she's waving at everyone like we're in a parade.
Good luck and keep us posted!