I race NSS, and the main reason I cut the choke horns off is to get more clearance on the front carb to the top of the scoop. I like to run the close to original scoop, not the over sized ones, and if you don't have the three inches clearance, my car will slow down.

I set my carb on the flow bench and started cutting and checking things, I got about 5 CFM by cutting off the choke horns, my bench would only pull them to 10 inches of water, and then I just converted to 20 inches, which I think is close to the 3 inches of mercury the carbs are rated at. my 750's flowed 670cfm on the bench at 20 inches. I do know that if you cut too much off the horn, you get a lot of turbulence around the top of the venturi's. So I just cut and kept checking with a wand with a string until I had a decent nonturblent flow into the venturi's. That wound up being about 1/4 inch taller than the ring where the air cleaner would sit.

I think the biggest improvement on my carbs was to use the velocity probe on my bench and solder a carb jet to a brass tube, and measure the flow or pull on the venturi, both primary and secondary, then swap clusters and/or polish them until they are all balanced as close as you can get them. I also pressed on a thin aluminum sleeve to extend the front venturi deeper into the body, like the older boosters were. My results were Front venturi’s flow tested at 10 inches, 194 to 198 feet per second on velocity manometer
Longer sleeves added to improve flow, improved to 220-229 feet per second velocity.

I got to run the car this weekend and the O2's showed a lot more steady AFR during the run than the other carbs I have used. And the engine made more power than I could reliably hook. Got it to run a 6.15 @ 112 mph spinning the tires with only a 1.40, 60 foot. in the 1/8 mile. On an easier run when I stalled at less rpm, it pulled a 1.33, 60 foot. So today I ordered some different rear springs, to loosen it up a little.