Depending on the DSO, most 390 GTA's got a Holly 4150, list 3794, Ford C7OF-B, carburetor. I think they were rated at 600CFM. The exception is wonderful California Smog cars delivered to DSO 71 (L.A.) or 72 (San Jose) where the Holly list was 3796, Ford C7OF-D. A vintage Holly would be bronze. Pay attention to the date code which is a three digit number used on factory cars, aftermarket or Ford service would be a four diget number.
Jim