To do 4-450 Hp with a 351W is tough to make those numbers without a good pair of heads, camshaft, induction system. Then the cast crank and big main bearings can be a major drawback to rpm. More to consider, but that's the basics. BUT, put your plan and a set of budgetary numbers together and let see where it goes from there as just throwing parts at these engine (or any brand engine) wont see those Hp figures