Blackjack, most Holleys have a big (3/8") PCV port on the throttle plate, either on the back or side...those would be the first choice. My Ford 2x4 manifold also had a plugged port at the back of the back carb pad where you can install a 3/8" hose barb for PCV connection. I agree that you shouldn't plumb into an opening into one of the runners, as you'll get all the
oil vapor, etc. into only one cylinder, along with an uneven fuel/air ratio for that cylinder. Also, seems that one vent (the "S" vent at the rear) should be enough...what if you put a screw-on
oil filler cap (a standard Chevy cap should fit) in place of the front vent and ran with only one vent? PCV would be better for a street machine, though...