[MOTORHEAD]

Just to beat a dead horse:
WDZ: Sorry for my brain fart, Lurk said the number was on the block. It was past my bed time last night !!!
Lurk: My Ford Industrial/Marine manual shows a part # D3JE-9424-AA for a two barrel 302CI. # for 351 is E6JE-9424-BB 4V.
Your # doesn't quite match the part #, and my 351's don't match either. I think what we are looking at are casting #'s as opposed to the catalog part #, but your casting # starting with D3 is not
a 351.
Also the block height behind the distributor seems to be definitive:
its a 302.
Good luck with the boat!!
Ted