Hot 318, carb choices.

Need some advice on which VAC SEC carburetor to run on my stout little 318.

specs are as follows

1967 Aussie VC valiant. (same as USA's 1966 valiant)
318 + 0.030" (323ci)
10.39:1 CR (KB399 pistons)
915 "J" Heads with minor bowl work
2.02/1.6 Valves
Comp Hyd Thumpr cam (227/241 @ .050")
Cast exh manifolds. Twin 2" pipes for the time being.
Edelbrock Performer RPM Dual plane.

Standard factory rods
340 steel crankshaft, full blueprint and balance on rotating assembly.

904TF with 3000-3500 Stall
3.7:1 final drive gears. 25 inch tires.

It's a street car 95% of the time, but I'm taking it drag racing in December and I believe the car should be cabable of mid-low 13's if I get the tune right. (I'm guessing)

It currently runs a 500cfm Edelbrock thunder AVS and seems to be rich all the time. I had this leftover from a previous 318 which was a standard high mileage engine.

With the 500 AVS it falls flat on it's face from idle til about 2000 rpm and probably isn't performing to it's potential up high in the RPM either.

If I'm going to spend time tuning a carburetor, I want it to be the right size for the application

I've been recommended the 750 Holley as well as the 650 Speed Demon.

There seem to be countless options out there.

I'd like to get some recommendations based on personal experience with a similar engine. no brand name fanboys please.

Thanks in advance, Frosty.