Replacing a OMC 800 with a OMC Cobra

Been out of the boat ownership scene for years but a friend needs some help. He has a 20 foot skiboat with a OMC 800 This is mated to a Ford 351. The outdrive has given up after recent rebuild and 1000.00 spent. He wants to replace this drive with a OMC Cobra which is attached to a Chev 350 that is junk. OMC 800 is 1977, Cobra is 1978

My question... What would he need to mate the Cobra to the Ford? My first response was replace or rebuild the Chevy and put the entire unit in. But that comes from far more experience with auto engines than boat outdrives.

He is going to provide me with model numbers on both for better reference.

 

Since so many of the OMC Cobra packages used the 351w Ford engines, should be a fairly simple matter to find the correct bell housing and shaft coupler. I'm in the opposite "boat" right now; trying to locate, without success so far, a bell housing and coupler to mate a 496 Chevy to an OMC King Cobra outdrive. The Ford engine parts for the OMC Cobras are much easier to find.

 

Thanks BMcf.. Well we got off to a very rocky start. After telling me about his Cobra outdrive. he sent some pictures. What he really has is a pre alpa "R" 228 Mercruiser mated to a blown Chevy 350. Sorry about that.
So lets start over.
Should we find a 350 and replace the engine and stern drive. Or what would it take to Mate the 228 Mercruiser to his Ford 351???
Whew.....

 

I think a new post is in order... I jumped in without knowing the correct facts.
thanks

 

The Merc "R", "MR" and Alpha drives are interchangeable as far as I know...but I'm no fan of the Alpha drives and less a fan of the earlier incarnations.

 

Really... So maybe my friend is barking up the wrong tree. Are they weak, or poorly designed or maybe both? This one is free but a long way from going to the lake.