If you do nothing else, check for rust. Look under the car at the sills, look inside the wheel wells, check the top of the door gaps at the rear. If the gap is tight on top and open on bottom, then the car is starting to sag. Bad news, unless you have a demented need to learn how to use a mig welder. That is my latest affliction since a "friend" who moved gave me his alpine. Oh yeah, also take a look at the ends of the X-brace under the passenger compartment. It starts to rust at the four corners. My car sounds like identical to your situation, except the brakes were dry and seized, the engine is stuck and the sills and floor are rusted to hell. When I towed the car a half mile home with a rope behind the tireless Toyota pickup, the fair and lovely Lisa used the clutch as a brake. She just put it in gear, and eased off the clutch - the seized engine stopped the car. I digress. Without any serious rust, I'm dumb enough to pay $500. You are going to totally rebuild the brakes anyway, because I hear some of the front clip is hard to come by. If the engine will actually start, $500 is a good number. Plan on doing all of the work yourself and enjoying it, otherwise it is cheaper in the long run to buy one in better shape for a couple of thou. Hope this helps.
Brian Corrigan 67 Alpine rust research study 72 MGB-GT daily driver