I personally liked an old 400 CFM Carter AFB carb I ran for a while.
Does the 12 port news state why a 390 Holley it is not a good choice? If not,why? Look into where they got there info from.
Maybe it's something new? New findings?
I ran 3 48 MM side draft Webers (3 two barrels)approx 1100 CFM,you would think it was over carbed, but it ran great!
4 BBL is a different animal,I never got good results w/a 600 vacuum Holley,ran better w/a 600 DP.
I ran both 625 AVS & 625 AFB Carter 4 bbl carbs & not w/great results.
I also ran a 800 CFM Quadrajet spreadbore & also a 1000 CFM Thermoquad AKA "Thermobog",Too big to run those carbs on a mild 250.
The best bang & not too much power on top or mid range was when I ran a Holley 350 CFM 2 bbl.
I would think a 500 CFM Holley 2 BBL would work good also.
MBHD