which Carburetor kit?

There is actually a formula for figuring out how much Cubic Feet Per Minute (CFM) of fuel your engine will possibly need. It's half of your maximum desired RPM (for street vehicles we always said 5000 RPM, so half would be 2500) x your cubic inches of displacement (so 318 ) divided by 12 cubed. 2500 X 318 = 795,000 divided by 12^3 = 460.07 CFM. That equation is for naturally aspirated engines. That equation is also assuming 100% volumetric efficiency, which doesn't happen. Just a useless equation I learned back in my racing days. 390 CFM should do just fine on a naturally aspirated 318. At 85% Volumetric efficiency, you would need 391.059 CFM