vacuum gauge to solve idle issue

Steve...the "old school" way of introducing more air through the carb at idle was to drill small holes in the primary plates.This, so that the plates can be closed more, allowing the idle circuit to come back into play....
ccrp_1104_07_o-holley_carburetor_rebuild-throttle_blades.jpg

...but, like AJ says, that was really only for fairly radical camshafts.