tunnel ram

Hello all. I got my car started after some head aches. Pressure regulator went bad and some leaks but nothing serious. Car ran very rich and the power valves would not stay closed because of low vacuum. I expected this because all I had were 6.5 pv . I ordered some 4.5s to try. My question is can I just block the front power valves and square jet the carbs. This is a race only car. Streetability not a concern at all. There are no pvs in the rear of carbs just 74 jets. Thanks.