I would opt for the smaller carb. The only large carb I have had any luck with is the Quadrajet (which is a fantastic option) but it is a spread bore and won't fit your intake.
Another small carb is the Holley 450 economaster. It is also a spread bore and has become obsolete, but can still be found.
Both of these can be adapted to the square bore intake.
Holley makes two square bore carbs in the range that would work best. Both the 390 and the 470 would be good options.
I have run both the AFB (Edelbrock) and 600 Holley's. While they worked, I never felt the performance was optimum.
Just my .02......