If you've got a Mercruiser engine, it's already got a pretty healthy cam in it. Some of them came equipped with Rochester 2-barrel carbs. I'm not sure if they used the flattop pistons or not, but it's a definite possibility. Did the engine happen to have that nice cast aluminum valve cover on it? Mercruiser engines usually had aluminum valve covers, and sometimes side covers, also.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!