Indmar, PCM, Marcruiser/wahtever doesn't really matter. They're all new from reputable companies. Not sure if they build them or buy short/long blocks nad finish them with marine parts. Maybe someone else knows? This would be a good insight into it.
Personally I prefer Ford 460. It's simple best bang for the buck engine and in a low output boat application they'll last forever. You won't find many in ski/wake boats though. After that would be BBC/454 based, followed by SBF then SBC. I wouldn't want to deal with Mopar since I don't know much about them, or any of the oddball GM motors.I'm a Ford man, but I wouldn't ever want a small block in a boat. Square peg in a round hole. How many guys here prop/gear the hell out of their boats to pull lots of weight? Yeah, a lot. I prefer to have torque on demand at all times without spinning to the moon. FWIW my boat has a PCM 454 which I think is fine. If it ever needs a rebuild I'll most likely replace it with a Ford 460 stroked to 545. This application needs displacement.