I've been looking at a boat that has a Mercruiser 350 with a cracked block. Can I use a regular Chevy 350 short block and transfer the other equipment to it?
It would be best to find a complete 'long block' (block and heads) since a cracked block could have also meant cracked cylinder head (and exhaust manifolds).
As Bondo mentioned, you will want to pay special attention to the camshaft in the donor block, as it would need to have minimal valve overlap for marine 'wet exhaust' use. Perhaps the camshaft from the original engine block could transfer over (?)