Quick Fuel carbs are owned by Holley, so they are one company. But QF carbs have always had features stock that Holley charged extra for, so I buy QF carbs myself. I have a QF 650 Brawler on my full roller SBC 350 with Dart heads, and a Howards roller cam, and roller rockers. It's around 420 hp, and 415 ft. lbs. torque in a fairly heavy '39 Chev coupe. It runs great and although I'd recommend vacuum secondaries for lower performance engines, for my build I like the mechanical secondaries.
Only thing I changed were the air bleeds as my engine idle was too rich, even with my idle/air turned almost closed. I put in #74 air bleed jets and I was able to adjust the mixture to where it burned clean at idle, and no more eyes burning!
PS-If you haven't checked Holley's website yet, I'd suggest going there before buying anywhere else! They sell 100% warrantied "factory refurbished" carbs for huge discounts. I spoke to a tech at Holley who told me the vast majority of warranty returned carbs have no issue when they're returned, but get thoroughly examined and tested, so they're great carbs. I bought my 650 Brawler for $210 new, vs. Summit and Jegs price of $679 new.