Thermoquad vs square bore
71duster, do they actually ahve T-quads available? I took a quick look and besides being a mainly GM carb biz, they offer an "aluminum Quadrajet to replace that problem Thermoquad."
You ay also want to check out: thecarbshop.com in Costa Mesa, CA. I have heard some really good things about their TQ work. I think at one time they were reproducing the TQ resin bodies (which had a tendency to warp over time). Re: your main question. I love TQs when they are set up correctly and if modified, I believe they can run just as fast as a Holley. Don't get me wrong, I love both and run both types.