I’m currently running a 1000 CFM, 4150 Race Demon (not sure it actually flows the rated 1000 CFM), which was built just before Barry Grant when out-of-business (maybe 2010). Additionally, I’m not running a throttle-stop, primarily foot-braking it and running it wide-open!
I’ve seen several posts with suggestions for different carbs (person preferences), however, I haven’t seen any compelling “technical criteria” exactly when you should run a 2-circuit, or 3-circuit carb.