While the max flow of most Qjets is 750 cfm (some are 800), the rules that apply to Holleys and such don't apply to q-jets. The reason is that the secondaries are actually operated by air flow, and if the air flow isn't high enough to open them all the way then it doesn't. It basically self adjusts its CFM from about 150 (for the primaries) to 750 completely automatically, delivering the right mixture across the whole range. A 750 cfm Q-jet will work on any engine from 200 - 500 cubic inches without changing much more than the idle mixture and speed. I put a Q-jet from a Buick 350 on my Jeep's buick 225 and had to do very little tuning.
