Swap 302 omc for 351windsor omc king cobra outdrive

I have a 1990 Donzi 23 GT Regazza with a 302 omc king cobra. i have two dealer that are giving me opposing information. On says i cannot swap the 302 with a 351 omc windsor the other dealers says no problem. any opinions out there or anyone done such a engine swap?

 

Don't know if something is unique about the Donzi, but a 302 will bolt up using the same mounts as a 351. Since the 351 is a little taller and wider the exhaust manifolds will be in slightly a different place - inch or so further apart. Drive should be identical. Shouldn't be a problem if you have the vertical space.
You could also go to a 347 cu. in. 302 for a LOT MORE power.

 

Thanks for the information had not considered bumping existing engine out. found company in costa mesa "outboard exchange" that can do the job

 

The 351 Cleveland is a direct replacement. I believe the Windsor may require some work.

 

The 302 and the 351 Windsor are BOTH Windsors. Only differances are "Deck heights" , bearing sizes and stroke.
Heads interchange as well as ALL externals except Oil pan.
The Cleveland is an ALL Together Different Engine, but WILL bolt up. Never heard of marine conversions in the USA - would at least require custom Exhaust manifolds .

 

This was done on my boat- only from a 289 (same block as 302) to a 351W. All parts swapped over without any problems except for the intake manifold. The taller deck on the 351W requires a different intake. I'm not sure if there is a difference in the heads or not regarding valve size and combustion chamber etc..(though I doubt there is one) ; but you may have to have the bolt holes expanded from 7/16" to 1/2". I do know that era of 302's and 351's both used the same exact head in their auto line aside from the larger bolt size in the 351W. Not a big deal. Even the exhaust lined up OK; being it's only around a 1/2" difference on each side.
- Tom

 

Just a side note. My setup was on a Volvo Penta; though I couldn't imagine yours being an OMC could make a difference in what block is used.
- Tom