You can do that and get a nice super low compression ratio and slow port velocity, great combo for a lower cubic inch engine to lose all tq at all. If you have ever driven a factory 4bbl 318 that had those heads you will see they are total dogs till they get reving and even then it don't make up for the lack of tq, the factory only did it for the emmision aspect. The only tim they will do you any good is with some way of brinngin the compression up a bunch plus running a cam that makes a 318 rev up pretty high.