OK, it does appear there was a 795-800 and 750, but 750 and 800 being the advertised QJet ratings as Jim said. But there is this info, and excerpt from a Rochester QJet study which explains the different CFM we'd hear of as being ACTUAL. I'm about certain I've heard of 780 QJets, and they may very well be in some flow bench testing #'s I've read about somewhere. But this excerpt does say, there were variations and Qjet could make whatever variations they want and detune a 750 down to 590, again, another off the wall #.
Based on my 3 months or so study, qjets had at least 4 different main body castings they break down into the following CFM ratings: 750 pre 1974, 795-800 pre 1974, 750 post '74 and 800 post 1974. For some smaller motors rochester inhibited the secondary air valve from opening all the way which could limit a 750 CFM to 590, or theoretically about any CFM rating they wanted. Actually when you really start looking around the bonyard you see lots and lots of funky variations of airhorns, chokes, etc. The principal variation in the main body casting which affected CFM rating was whether the primarys have a diameter of 1 3/32's inches or 1 and 7/32's inches.
So this tells me, if your primaries are 1 3/32nds, you have the 750 rated variant, if you have the 1 7/32nds primaries, then you'd have the 800 rated variant. But to answer the posters question, I'd say go with either one, the 750 or the 800 because I have seen both on 454's, but usually the 800 cfm is rated for the earlier 70's and I don't see a peanut port head motor needing an 800cfm.
