Will the bore and stroke be the same as a D353? They are 6.25"x8" and redlined about 1200-1225 rpm which is my favorite thing about them. Much more enjoyable to live with on a boat rumbling at 800 rpm for long periods of time compared to a Jimmy whining at 1500. I know you're not building a D353 but in case anyone's interested here's a spec sheet for the marine version:
http://marine.cat.com/cda/files/1014...lsion.pdf?mode