any 6 pak gurus out there?

Put a vacuum gauge on it with a long hose and tap it to the windshield, drive around and watch the vacuum. My guess is the PV is open most of the time, take a long piece of vacuum hose and put it in your ear and run it around the base of the carbs and if you have a vacuum leak you will hear it. Plug your PCV valve hose and see if the vacuum comes up, Ive had a bad PCV valve cause problems.
Her is a good read on CFM, It is not cut in stone
Carburetor Air Flow Ratings