Like Capt. Bob said, if the tank is original, plan on that in the near future. It has a 120 gallon tank. Most likely around $1,000.00 to $1,500 if you go back with original tank.
Like all older boats the transom is most likely wet, but how much remains to be seen. I would take a buddy with you and have him stand on the motor and bounce up and down while you are looking down the transom for any flex. Check for stress cracks where the splash well is joined to transom.