Not too sure what a "marine cam" is. For every boat I've ever owned the cam was picked with the same questions answered you would when picking a cam for a car.

For the boat you need to know heavy, what bottom profile, what drive type, ....

For the engine you need to know compression ratio, intended RPM range, head design, induction system, ....

Then usability -- how is the boat used, who will be operating it.

There may be a few specialty "marine cams" offered by a couple of the grinders, but usually you'll find the same pattern elswhere in their catalog for an automotive application.

Cheers, Mark