Don't know about 2 of the 150HP but one of these will fit nicely:
https://mercurymarine-gsdesign1.netd..._370_tier3.pdf
It is a twin turbo 4.2L 370 HP VWMarine engine with a Merc label. Brake Specific Fuel Consumption is about 40% of what it is for a small block chevy and it weighs about the same. I'm pretty sure it costs a good bit more though...