When I learned to fly back in 1981, I was in the airport bar (under the control tower) and on the wall was framed story with pics of the events of these aircraft.
Tony Schwert (who i believe still flies VH-URU up to Beverly in SA) tried to persuade the Govt in letting him purchase these Mustangs, and stick them on the Oz register. Bollocks, was the reply, so he ended up purchasing them, tying them nose to tail, getting a bulldozer and dragging them down to the East-West railway line and loading them on the train, back to Parafield, crated and sent off to USA where this warbird movement was gaining momentum. He did however, fly one with gear down to Parafield, and that was the main photo on the wall.
That's the story as I remember it, and it may be missign bits and pieces, but I am sure there are a load of guys around in SA who know Tony, or maybe you could even contact the guy himself.