Carburetor cfm for a mild 318 build

Your combo picks looking good

Mph x 336 x gear ratio / tire diameter = rpm or rpm x tire / 336 x mph = ratio

tire sizes make a big difference, with a 26” tire my preferred gear would be 3.91 but you can go higher like 3.73 3.55 or 3.23 just with performance losses.

26” with 3.91 = 28” with 4.10