I have a Quickfuel 750an on a Performer like yours. I got it because of the an boosters but it's fairly rich even after tuning on a chassis dyno. I think someone on the forum recommend changing jet sizes somewhere, which I need to do.
Have you thought about the Holley 700 modified by Larry Stock at Pantera Parts Connection? Its listed as having many Pantera specific changes. If I were to do it again I think I would've given it a try.
They discuss it about part way down the tech tips page.