I found myself making a similar calculation recently - I have a project car, and when I dragged it out of a field and hacked the vegetation out of the engine compartment, there was a 40mm motorcycle carburetor mounted to an adapter mounted to the intake. The carburetor even had a Harley-Davidson logo embossed in it.

I wanted to put a two-barrel Weber carb on it, which had a 36 mm and a 32 mm throttle plate. The 40 mm motorcycle carb had an area of 1256 mm^2^, while the combined area for the Weber was more like 1820 mm^2^.