Usually rust is the main problem with Squarebirds. If you don't have to do anything like that you are way ahead of the game. The main problem with SW cars is the interior so unless it's been replaced recently that will cost you a big chunk of your budget. Doing a complete interior restoration is expensive mainly because of the padded dash which runs $400. Seat cover sets and door panels are also expensive. Figure $2000-2500 if you do all the work yourself. If it's been sitting two years or more then plan on replacing all the brake components as well as the gas tank, lines and fuel pump. I wouldn't be as concerned about the motor. I've had ones that sat for 20 years and still started right up and ran fine. They usually leak oil like a sieve from the intake and valve covers though. As long as the price for the car is fairly low you should be ok.