If you have the dual pattern Performer, I tend to agree with Calgary Redneck. Q-Jet is perhaps, the best carb ever made by anyone. I know, I know... "Quadra-Junk". Only in the hands of someone not skilled in rebuilding a complex carb! Send it off the Cliff's Q-Jets in Ohio, and see what magic he can work! Many a 10-second Pontiac-powered Pontiac out there with a Q-Jet on it.
But if you have the Performer with only the Holley flange, I would feel you lose more by an adapter, than you would gain by the good design.