For valve covers, there may not be much difference. Marine engines typically use heavier duty internal parts and/or different water pumps and exhaust manifolds to accomodate cooling. This could also trickle over to valve covers if there is a need for additional crankcase venting, like an additional pcv valve or something, or additional/different wire looms. If you want the exact, correct year, style, so on and so on, then these probably won't be them. If you just want a stock appearing stamped steel valve covers, these would work.
