"I would avoid raw water coole
"I would avoid raw water cooled engines run in salt water. Exhaust manifolds don't last very long in salt water. There are some fresh water cooled I/Os but they are not very common. Boats that stay in the water all season may be prone to electrically induced corrosion on the lower unit. Avoid anything with pitting on the lower unit itself. A boat kept on a trailer can be in fine shape. I've owned I/Os, inboards and outboards that were run in salt water. Conditions will vary widely depending on how they were used and maintained. Look for a meticulous prior owner.
The 2 happiest days in the life of a boat owner are: The day he buys it and the day he sells it.
Good Luck.
Chuck"