Off on another tangent,.....
How about an Allison V-1710 powered Whirlwind? Have the Turbosupercharger be part of a quid pro quo of the Tizzard Mission?
Turbos were very large, Whirlwind nacelles small.
Better would have been radials, like the R-1830 Twin Wasp.
slightly more weight and frontal drag, but 200HP more at this time and dead reliable