The basic pump is the same up to 375HP, but there are some differences in the governor and in some csase the camshaft , so be careful what you are buying, the settings and governor springs will be different. Above 375hp, the marine pump is different, it has larger pump elements and the one with smaller pumps just will not deliver the horsepower.
Catsilver, Thanks for your response. I will steer clear of a "road" solution. Peter.