From my exposure I have to say Holly carbs are terrible unless your a carb expert and like rebuilding carbs every other year, They are hard to tune compared to edelbrocks. The thermoquads and Quadrajets are all-right carbs good for a stock application, and I have had/seen best luck with edelbrock and carter carbs. I have also had bad luck with mikuni carbs, and good luck and easier tuning with Kehin carbs.
1986 ATC 250R(for sale), 1963 AceCraft boat w/40HP Evinrude, 1981 Arctic Cat El Tigre' 440 L/C, 1992 GMC Safari Van.