something to ask is where was the boat stored, inside or out, and back then, wood was used in the transom and floors. If the boat was stored inside all the time, should be ok,, but if stored outside with no cover, the floors/transom may be in question. You would have to inspect it closely, get in the boat and bounce on the floor, etc., and with a 75 it should run great. I have a PT175 w/ a 60 2stroke, and it runs in the mid 30's. Solid boats if cared for.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.