This is a good subject, one that will need a lot of input from others.
A couple thoughts.
Auto swaps. I’ve never swapped out a pedal box but I imagine a manual/auto swap would be harder, considering the diff has to go too, then an engine swap. It’s easy to imagine someone selling an auto e30 with serviceable drivetrain for $1500 and a manual e30 with a bad engine for $500. I’d take the manual with a bad engine. The reason I bring this up is that there’s usually more auto e30’s available then manual.
A compression test is a great idea, but it requires some experience because it’s a “relative” test. So you need to have done it with the same gauge on the same model engine with the exact same test protocol numerous times. That gives you a body of previous test results to compare the test to. In the absence of that experience, all you’re going to see is a piston that differs from another. Good “relative” info, but not “absolute” info which would be ideal.
Rust. The bumper rust idea is a great one, but removing a bumper that has never been removed before can be a bastard at not worth the hassle. IMO you can see what you need to see re. bumper rust simply by getting under the car and maybe using a little inspection mirror. What you want to see is that the frame rails around the shock mounts look like they’re still reasonably stout.
The rocker panels under the doors get beat up by shop lifts. There can be rust-thru there hidden by car’s undercoating. That undercoating can also hide rust in the wheel wells.
Don’t walk away from a car just because of a little bit of rust. Try to figure out how much strength remains in the steel piece that is rusted. In many cases as long as you don’t have “rust thru” you might be ok. Wire brush off the worst of the rust, brush on a “rust stopper” chemical, paint and drive on.
- A bunch of dings everywhere is worse than awful paint. As long as the sheetmetal is fairly unblemished MAACO will happily spray your car for $500 or so and it will look fabulous. Sheetmetal that’s all dinged up tho is a pita.
Fenders and doors are easy enough to replace, so if you see a car for dirt cheap because of a beat up fender or door, that could be a deal.
The cheap and easy way to get in a race car is to buy a race car. Or buy someone’s unfinished race car project. There’s someone in S. FL right now selling a caged shell for beer money. It’s ugly, but fixing ugly is a helova lot cheaper than a cage. I think I saw it on the NASA-FL Facebook page.