Definitely want the transom, stringers, cockpit floor, thoroughly checked by someone that knows what to look for. If boat has trim tabs, or a transducer mounted on bottom rear of transom, removed one or more of the screws holding these items on and see if any water comes out. Check the screw you removed for signs of wet wood. If seller will not let you remove and reinstall a couple of these screws, run away as fast as you can. Walk around every inch of cockpit floor area checking for any soft spots. Especially on the non-removable areas. They will be very hard(expensive) to repair. Check bottom of boat for blistering and prior damage. A fresh coat of bottom paint should be viewed very suspiciously, as it could be hiding a multitude of severe problems.
Check wiring and electronics integrity. Boat is 27 years old, has wiring been butchered up? Check engine for compression, hours, etc..
This boat could be in very nice shape and give you trouble-free use for years, or it could be your worst nightmare, that you can't wait to get rid of, if you can. Be diligent, and check it out thoroughly, or have someone else check it. Just my opinion. Good luck, Mike.