The Mercruisers have the same bellhousing mounts as the automotive models - they used a special "mini" housing. Some of the 292s used a hotter cam and 4-barrel carb but I don't think the 225 HP rating is correct, the standard 292 Mercruiser was 175 HP, the performance model was 200 or 205 HP if I recall correctly. Other differences are that the intake and exhaust manifolds are water cooled (expensive) and valve cover and pushrod covers are alloy castings.