Can you take a 4.8 Cadillac engine in pristine condition and maranize it to a 377 or 400 chevy, If yes, How ?

Any engine can be marinized but it may be cheaper to buy a factory marinized one.

1. 377 cid would make a 6.2 liter motor. do you honestly think you can oversize a motor that much and have ebough clyinder wall left to handle the explosion occuring in it repeatedly for long?

i wouldnt even try to get that much out of a 5.7 liter, IF i could find somebody willing to do the machining.

2. its cheaper to buy one already prepared for a marine life, or just use it as is and not expect it to last long.

3. i believe a caddy motor has a different bolt pattern basically everywhere. and i would be suprised if there are parts to adapt it that will work in a boat application.

no caddy uses a different bell housing and completely different parts internally