I'm no expert on carbs or Qjets, but I was under the impression that most of the Qjets were the same, around 800ish cfm, small primaries, big vacuum operated secondaries. Could be wrong though...
The Mirage is a good 3 blade prop and should give good top end numbers if it's the right size. If the boat is having slip problems out of the hole or blowout during sharp low speed turns, a 4 blade Bravo might help. The 4 blade can also settle high speed manners as well but you would likely lose a mph or two.
-brian