440 Build Plan

yellow rose said

It’s about lift and valve speed, and not so much about flow.

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Not exactly. Lifting the valve as far and fast as you can is precisely so that more air will flow into the cylinder! Like I said, the ideal lobe would be square. Instantaneous opening of the valve, staying at the desired lift for the entire intake event, instantaneous closing. Which obviously doesn't exist with a real-world lobe, lifter, pushrod, rocker, valve/spring.
There is always a limiting factor somewhere between the atmospheric pressure and the cylinder fill - whether too small a carb, restrictive manifold, intake porting, etc. So your heads are maxed out at .500, ok. The reason for using a higher lift cam is so that the intake will spend more time at and above .500, thus maximizing the volume of air drawn in. And at some point the cam becomes the limiting factor (beating up the valve train, too much overlap, coil bind, piston clearance)...