I would go with a 750 vac sec. maybe get an aftermarket main body with adjustable air bleeds and secondary metering block.

My experience with the HP carbs (950...not sure if the 750 HP is the same or not) is that they use different metering block, with idle restrictions, power valve restrictions and emulsion tuning that are tailored for the track, not the street. Great at WOT, but pig rich at part throttle out of the box.

Also with 3.23's I imagine tuning transitions would be a bit easier with a vacuum secondary