There has never been an Overland painted NR so that leaves that out!
There was a design worked out for an Overland NR which was published along with those for the Ghan, Indian Pacific and Southern Spirit.
Of these, only one IP (NR 18) and the two Southern Spirit locomotives were actually painted.
The Overland version was very similar to the Southern Spirit with shades of blue instead of green with a silver cab
I'm sure they'd sell enough to justify making it, even if they never got around to painting the prototype.
The Ghan loco had shades of red in the Southern Spirit pattern, and was replaced on the prototype by plain red with the new style lettering.
But there are official painting diagrams to copy, so it will be authentic.