there are a # of factors here , first the 6 pack is rated as a 2 bbl not a 4bbl so the real flow rated as a 4 bbl is closer to 950 CFM total not that it will limit the power you want to get .
using a larger center carb is not really a benefit either , the small center carb has great throttle response & will get decent milage as well . The outboard carbs are difficult to rejet unless you get the Promax conversion plates .
Honestly I have found a single 4 bbl & the Holley Street Dom intkae or the Eddy RPM intake will make more power & cost less then the 6 pack , but having said that I also have a 6 pack on my 440 right now but I also have a 950 HP carb & street Dom put aside if I decide to swap it out , the 6 pack looks killer for sure