600 vs 750 Holley

I have 66 Cuda with 360 280H magnum cam edelbrock airgap intake. I had both 600 Holley and 3310 Holley on car. It runs better with 600 but was a lot quicker with 3310. The 600 is still on the car but I'm goin to try to tune 3310 on it when I get a another chance. For the street the 600 is better. IMHO