USRA light mountain driving wheels

Hi Guys,
I'm awaiting the arrival of the Bachman N scale light
mountain in the hope that it may act as an appropriate mech
for a NSWGR 57 class (down under, here in Australia). What is the
driving wheel diameter for these locos and the driving wheel base??
I've done a quick google search for drawings and plans for these locos
without success.
Cheers,
Roger Gillard