Yup, the A.V.G. P-40's were special, and it sounds like Shilling did do a yo-yo. Still, if you compare an AH F4F-4 and the P-40B, there is no move you can do in the P-40B to beat an F4F-4 in any kind of turn fight. The assumption is that the RAF and especially the Finn Brewsters were better than the Navy's F2A (they were lighter), which by some pilots was thought to be better than the F4F-3, and the F4F-3 clearly had better performance than the F4F-4 in AH (same power, much more weight than F4F-3).
What this really illustrates to me is first hand pilot accounts, though interesting, are not too helpful in evaluating plane performance in general.