Ok, and for the big question.

Should I even consider staying with that shaft in a lake use boat ? Assuming it checks out good. Or just go through the work to step up to a 1" shaft now before the strut goes back in. Changing to a 1" would require a new (or modifying) the coupler, and possibly a new strut (I haven't measured the strut barrel yet to see if a 1" bushing will fit). I could see that shaft being very expensive to duplicate if anything ever happens to it in the future.

I don't plan on running the blower anymore so hp should be around 600, and the boat is fairly light (small stringer) Daytona flat.