Its really NOT the flow number that is the key here. Its the cross section. 420 cfm will make 1000+HP, in the correct application. Basicaly, on a 632, that head can't be made to big. Regardless if the you pick up flow or not, it will make more hp the bigger you make it. Will the engine make as much power as it could with something else, no, but even a true 950hp is a pretty brutal amount of power. Its funny how guys that have never expierinced even 500hp, will tell other guys how 950hp is weak for some given parts.
If I am not mistaken, these are the 365cc 26 degree heads correct? With a 2.325-2.350 intake valve, some serious hogging, those heads could make 1000hp on a 632, or close to it. How much power you looking to make? Are there better heads to start with, absolutely, but, that head can be made to work if you have them, and, are not going heads up racing, and are trying to dominate a certain class, then, no, that wouldn;t be the head to run, but, if this is a bracket car, or something similiar, then, they can make a lot of power.
Frank
Advanced Performance
www.get-ap.com