Cool! So this would be the origin of the Stearman X-70/XPT-943 and NS-1?
The usual story says that the Stearman Model 75 began with the X-70 which, in turn, was a refinement of the Model 6A Cloudboy. Your text specifically mentions "Model 6L-1" ... so, more specifically, the Model 75 was a Model 6L derivative.
BTW: The name was Kaydet not 'Cadet'.