Ok this is a noobish question but honestly I do not know the answer. I know for a fact the electrical systems (wiring, alternator, starter and such) are different as well as the exhaust manifolds and as far as I can tell often times the cams are different too (higher duration I believe??) as well as the cooling system but beyond on that stuff are they really all that different? For a guy like me with a engine budget measured in hundreds not thousands, what would need to be done to a motor pulled from a car especially the cooling system. I have a very basic understanding of how that all works but putting it into use is another thing. Also the starter is kinda grey to me as well, never had my family's old 1988 Mastercraft down far enough to get a grasp on the difference there either. I am asking this because I am getting alot of interesting offers on project boats here but they all need motors. And I so happen to have a AMC 258 I6, Ford 302, Ford 460 and a Chevy 350 (EFI with electric fuel pump not sure if thats a cause for concern for marine applications or not) sitting around. Some bolt on stuff doesn't scare me at all but I figured I should ask folks who know more than I do about this before I get too gung-ho and get in over my head.