crawl under it and look for any rust/rot under the car. frame rails or suspension attaching points are a deal killer for me. look in the trunk especially the spare tire well. look closely at the window frames. then check the lower parts of the front fenders. lower corners of doors and the lower edge of rear quarter panels. if it is what he says it is with a solid body then i would offer him 2800 and then work your way to 3k if he wont budge.
a solid foundation will save you a ton of money in the long run.