Tom, that is one of the best ways to look at IMHO opinion. Also most of the better heads have an altered intake valve placement, which even further reduces the shrouding. This also depends on the amount of free drop the valve has. Canfield has an altered valve placement,IIRC its .200 toward the center of the bore, TFS TW does the same, but with a rotated valve also. AFR's have a stock placement valve, there flow numbers are inflated, due to the fact that they flow them on a larger bore. Most other heads use the standard .030 bore for flow numbers.
Valve shrouding in the combustion chamber is far more important I believe.
I have a set of Canfield 195's, they are 2.02/1.60 valves, its on a stock bore 302.