I assure you I have no direct answer. But a 300HP Bravo 3 I/O does well with the 25 seafari- ~27-28kt cruise. So I think you are in the ballpark if the center of mass isn't terrible.
edit: clues here:
http://www.classicseacraft.com/broch...ure/index.html
http://www.classicseacraft.com/broch...ure/index.html
Max allowable HP 600, wweight 7000 lb, rated for dual 2.6 OMC sea drives (2 x 175hp-200hp) or a pair of real outboards.