Hi Bryson,
my old car - which was Clare Glasson's Richards Bodied 39 is coming up for sale in the UK at Historics at Brooklands in a few days.
See ebay UK item number
162159452361
Anyway, you can see the correct handles for your car are the plastic covered ones. Because your car is Australian assembled, you may find that Richards made and used their own type of window regulators in the doors and a US one may not fit. Also the mounting of the handle may be different from an OZ car to a US one.
I can't quite remember if Clare's old car was a notched thread or a square mount. When I am home, I will see if I can find a more detailed image.
Regards
Greg