While it is always possible that the NA-50/P-64, having already flown, might have served as inspiration to Lawrence Wackett in late 1941, there has been no evidence turned up in the last 80 years of any direct link back to the NA-50/P-64. The license held by CAC from NA allowed them to develop the basic NA-16 airframe as they chose, which is what led to the Wirraway. That is what they set out to do in Dec 1941 using an airframe (Wirraway) and engine (R-1830) already in production in Australia. Given the crisis, it makes sense really.
The Wiki article draws heavily on Francillon's Profile publication from 1967 and later research.