Consider a professional surveyer BUT..
...they ain't perfect:1. check for routine stuff as on any boat this age like standing and running rigging, sail condition, anchor and rhode condition, fitting of compartment hatches (my cockpit locker is a constant pia as it was misalligned at the factory), hull moisture and soft spots (on deck too), amateur repairs or electric work, too clean (to hide leaks) or too dirty, bedding of hardware, engine,2. swing keel should work smoothly with effort and drop slowly when stopped and not get hung up, may be a bit of side to side wobble3. roller furler may have been installed with tangs if so make sure headstay is not too long as it should have been shortened,4. as mentioned check bilges (under rear birth and both sinks) when heeling hard and after doing such, the top of the tank (and accumulated water) can be seen in some boats by opening the teak step on the campanionway stairs and shining a light inbetween the inside of the step and the tank extension for the controls,5. wrap dry paper towel on the tank controls as per above heel hard to check seals, 6. sail upwind hard to check tension of shrouds, should not go slack, if they do then check to make sure they can be tightened otherwise a simple or complex problem exists,7. while sailing hard upwind, check for rudder creap (yea CREAP not creep), if he exists, no big problem lots of fixes,8. consider spraying a hose at hull deck joints, hardware and ports to check for leaks,9. what everyone else has or will say. alan