[SwiftDB4]

Go with either QF or Proform. Proform is made by QF, just cheaper, but same as SS QF models. Don't mess with Holleys unless the tuner has modified carb for replaceable idle fuel restrictors and both idle and main air bleeds. With 10/1 A/F you definitely need more adjustability than just main fuel jets. I ditched my Holley 770 vac sec for a Proform 750 mech. Had to reduce idle fuel restrictors and increase main air bleeds, but well worth it. Engine (Roush 427SR) runs 14.5/1 cruise and 12.5/1 WOT. More power and 25mpg on highway!