That stock 235 with the Holley one barrel photo I showed earlier pulls 19-20 inches of vacuum at idle.I also have a modified 302 GM,fairly hot 3/4 cam,it has a pCV and idles at 16 inches of vacuum.
In my opinion,the PCV isn't so much a vacuum leak,the air through the PCV just replaces the air normally metered by the throttle plates at idle.Otherwords,pull off the PCV hose,plug the port,ya need to turn in the idle throttle stop screw a turn or two to get the idle speed back where it was.Generally,then you make a small adjustement to the idle mixture screws,not like you're screwing then in or out 3 turns.
