Theres something called a “bilge blower” in boats with a engine inside the hull, the exhaust manifold is marine-specific, its water cooled. Theres no air cleaner but a metal spark arrestor made up of thin metal plates, (in case of backfiring). the starter and alternator are supposed to be sealed in a manner that prevents any bilge fumes from being ignited. Back when point distributors were used they only had a mechanical advance, no vacuum. It’s possible theres a “marine profile” camshaft but other than that, theres not much difference between a automotive engine vs a stern drive boat engine.
I have seen 2.3 lima’s in boat application, back in the late ‘80’s starcraft had a aluminum cabin cruiser/fishing boat called the islander. Most of the 19-22 ft ones I saw had the 2.3 lima, I think their rating in a boat was 120.
Boat horsepower ratings seemed to be higher than automotive, the chevy 350 was rated at 260 back in the day, a 454 was 330.
I have no idea what is up in todays boats, I worked at a family owned boat dealership right out of high school in the late ‘80’s to the mid-90’s.