OK now I know what the engine could be, and should be that makes life easier. We have a company in the uk called British American Engines, who rebuild the following engines
Chevy 5.7 and 6.3, the 5.7's come in 250 and 270 hp and the 6.3 comes with 300 hp they also do a magnum 5.7 with 330 hp and the 6.3 with 350.
This company offers these engines marinised and ready to go!
They also do the following engines from ford, 302ci, 347ci and 351ci.
All these engines are "tweaked" for more hp, and I guess it would be good to know what the hull can take, as in the UK you can have problems with getting insurance if you over HP your boat. They can however rebuild a basic engine.
Just for fun, this is what 63,000 bucks would buy you in the UK!
http://www.boatsandoutboards.com/view/F175285
and the best part of 13,000 bucks would get ya this beast
http://www.boatsandoutboards.com/view/MOR252
Ollie