Weeelll....valid reasons, but it's a good idea to fill and re-drill mounting bolt holes 'cuz even a millimeter of difference in the size of the new bolts vs the old (think new "made in china' vs old "made in USA") can leave you with a wobbly pump. And is there any reason why the pump handle HAS to be straight out? Or that the pump HAS to be in the original location? Boat builders don't always put stuff in the best place...more often than not, things go in the easiest places to put 'em.
Not trying to be argumentative, just trying to open up the possibility of additional options if he can't find an identical replacement?