Yes big spider monkey problem!
Seriously I can say there were little to no spider cracks in mine.

tuliping the valves a issue on small blocks with that kind of hours...as said before compression test would help ck that...

The last thing you need to worry about in that boat (or most boats) is the engine and drive. You are worrying about the strongest link in the chain. If it is fresh water 500 hrs is nothing.

I have never heard of scoping the camshaft,can you give some inforation about that?

Hillbilly terminology for stress cracks in the shape of a spider web .

They drill a hole through the oil pan and or the lifter valley, drop a bore scope in and take a look. It is recommended every 200 hrs

Also the OP is 5/10 on on the Darr meter, interested to see where this ends up