850 cfm proform carb on 318!!!!

With the Thermoquad arguement you're not just the spread bore deal, but a mechanical secondary Holley to a air-valve secondary Thermoquad is apples to oranges. The T-quad has the capacity to flow 800 or 850 cfm depending on the throttle bores. But the engine only uses what it needs, even if all the throttle plates are wide open. Same principle applies to a vacuum secondary Holley, and both the counterweighted AFB and air-door AVS Edelbrocks.