I need some help with carb size thing is I have to holley carbs one a 600cfm the other a 750 cfm Im not sure which to use though. My 429 is a 1972model and it only has a 8:5:1 cr, it is all stock internally, even cam, the only mods really, are no smog, or egr, no a/c , timing advanced, 1" carb...