Not enough information, a number of marine engine and generator brands have used kubota powerplants over the years including beta, universal, westerbeke, onan, lugger, northern lights, etc. The parts most likely to wear out or fail due to the marine environment are the marinized specific parts like the watercooled exhaust manifolds, heat exchangers, raw water pumps, etc. So depending on who marinized the engine, the answer may be very different. In some cases you may be able to retrofit another brand's parts but you want to do the research ahead of time. If the installation used a dry stack exhaust and keel cooling, it would be possible that engine truly is an un-marinized tractor engine and you would be good to go.