A 377 (400 with a 350 crank) would probably be the easiest way to make 450hp. In order to make that much hp, you're going to have to have an engine capable of running a lot of rpms which would make me shy way away from the 365. That's way too much stroke for a little tiny piston. The 350 and 327 will have to run 6500-7000 to make that hp. You could probably get away with 6000 with the 377 and it's a whole lot easier and cheaper to build a 6000 rpm engine than a 7000 rpm engine.