Race Demon questions

I have a demon rs, with three sets of sleeves. A regular Holley 750 dp, 4779 has 1.375 venturi, 1.687 throttle. My red sleeve, rated 750, is 1.400/1.687. Blue, rated 775cfm, is 1.425/1.75. Gold, rated 825 cfm, is 1.500/1.75.
I bought mine from a friend who told me it was 850 cfm with the blue sleeves (I'm sure he thought it was, he wouldn't have lied to me). Took it off his 408 off brand, put it on my 406, went a best of 6.32/108 without ever taking the bowls off. I was happy the way it worked.
The gold sleeves and downleg boosters would go in, if it was on a bigblock.