318 Carb Size Question

Gents

I have a stock bottom end 318 with stock cam. I have .040 decked 1.88 "J" heads with an Eddy four barrel performer manifold. I'm running Hooker headers and full dual exhaust with electric MP ignition kit. I currently have an Eddy 500 CFM carb. Seems to peter out around 5,000 RPM. I'm thinking it needs a bigger carb?



I found a deal on a 650 CFM but didn't know if that would be too big? The 650 has vacuum secondaries but wanted to get some opinions.

Thanks guys