Find someone with a KNOWN good carb, ANYTHING, find a holley 600 vac, and take that one you have off and try it.

The regulator you have is a POS if the pressure is creeping. If you set it at one pressure and it goes above that pressure, it's really not doing anything worthwhile! If you could only handle 100 pounds of weight while moving something from one hand to the other. That weight is regulated and the system suddenly decided to send you 150 pounds of items, what's gonna happen? Likely failure...

Timing, balancer, fuel pressure, carb settings, vacuum leaks and who knows what else is a problem you have.