I have a friend who has a mercruiser 5.7 with a cracked block. It is a GM 350 engine.

Finding an engine or short block has been a problem so we are toying with the idea of building GM 4 bolt main truck block with the good parts from his engine.

I know that for most RV/Boat engines they used beefier heads and occasionally beefier blocks.

Would a 4bolt main block from a truck do the job or are there other issues?

Thanks