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