Personally I think with 3.55 or 3.73 gears you should be in the high 14s-low 15s. I am basing this on a friends 70 Nova with 255 hp 350 with 4 speed. Using a 6 cyl or vega torque converter is a cheap way to raise the stall, but don't expect it to last too long, especially driving it on the street much. Been there and done that. Be sure to run the biggest/best trans cooler you can get. I agree you don't need that big a carb, but if it is vacuum secondaries it may be ok, they only open as much as the motor will pull if they are set up right. For a 350 turning 5500 RPM a 600 CFM should be plenty. Why not get the Edelbrock carb that matches the intake? They are designed to work together.

Good luck with your project.

Pat