That should be 182cfm base on the engine outlined at 100%VE.
A 504 at 2200 rpm and 100%VE would be 320cfm. At 80VE the engine would require 256cfm. Double the rpm, double the cfm z9assuming the same VE at both rpm's, not neccessarily a good assumption).
Not saying the Case is that efficient, just grinding out the numbers.