ElCaminoFred

I have a '72 El Camino that I bought a year ago with an older ZZ3 crate motor. Engine runs great with lots of power. But due to only getting 9 inches of vacuum, I replaced the Holley carb with an Edelbrock AVS. I also reset the MSD distributor to give 18 degrees advance all in at 2800. I also reset the initial timing to 16 degrees. Vacuum is now up to 15.
I tried an acceloration test to check the new Edelbrock carb for flat spots. Power was instant and it lit up the rear tires with no hesitation. When I opened the hood after the run, the dip stick was 1/2 way out and the pvc valve was blown out of the valve cover (both on the pass side).
I haven't put many miles on the truck since I bought it so I have no data on oil consumption.
THE QUESTION: Other than bad rings, is there anything else that could cause so much crankcase pressure? Something plugged? The engine apears to have all of the '72 emissions stuff except an air pump.