Summit M-series carbs absolutely wreck the AVS2 in every department. For a stock motor, the 500 cfm version is fine, but with even mild mods, I’d probably go 600CFM, because you’d get a little less pressure drop and a little more top end out of it at WOT. The annular boosters ensure excellent fuel vaporization, which means a really clean burn, smooth idle, part-throttle,and throttle response that’s every bit as good as your average fuel injection setup. The M2’s are also inexpensive, at about $300. They’re a descendant of the old 4100 Autolite, but they use common Holley jets and parts. They are incredibly friendly to tune, as well.
All in all, these carbs are flat-out superior to anything else you’d find for under about $600.