Flat tappet cam?
30 wt with zddp additive.
Static time the dizzy.
Use a known good carb.
Good/fresh fuel supply.
Water supply with a valve close to the boat.
Vary rpm ,2000 to 2500 for 30 minutes. LET ENGINE COOL before it gets fired up again, preferably overnight.
Change break in oil to Delo 400, 15W40, with additive.
Go boating.
Dan'l