If the pistons are .005 above the deck(440 stock stroke) and those 452 heads are 90.0 CC or so I would worry about pinging and detonation with the iron heads on pump gas I have dyno tested similar combinations with 9.5 to 1 or so comp ratio on premuim CA pump gas with the Torquer II versus a M1 single plain versus a Eddy Performer RPM on the same motor, same day, same carb and fuel, the Torquer II was the weakest on torque and HP all the way through the RPM range, 2500 RPM to 6000 RPM IHTHs