I have a 68 Fastback with a balanced and blueprinted 351W in it running the Edelbrock Performer RPM cam and intake manifold. Heads are World with 2.02 intake valves and compression is 10 to 1. Hooker headers, top loader and a 3:50 detroit street locker rear. Currently have a little 600CFM Holley with vacuum secondary and would like to know if anyone has any experience with these other brands of Carbs. I lean toward the Demon but the Edelbrock is cheaper and the Holley is something I'm very familiar with. Love to know if anyone has tried one versus the other. You can't read the magazines because they tell you whatever the advertiser told em. Thanks.