If your class allows you to run a Quadrajet or you are just sick of working on that other brand, check this out. These Jet Performance Q-jets are extensively reworked by removing the choke hardware, increasing the main well size, enriching the fuel curve and adding a .149 needle and seat. They are rated at 750 cfm and work best with 355-406 small blocks with a single plane intake, headers, 11.5:1 and ported heads. They like a cam with at least 250 degrees of duration at .050" and .525" lift.
455-35004 Instructions (PDF)