Hi Ray, what part of Qld are you in? I'm in Ipswich. There's a few other ex-pats and natural Aussies involved in this forum too so expect the usual light-hearted banter at times, particularly around Ashes test time (we won't mention the second test in Adelaide which finished today!)
There are a couple of other people on this forum also interested in the 1831 and a mate of mine in Ipswich is building a Wallaby too but just out of interest in the engine itself, not to go in a loco.
I'm building a 5-inch gauge petrol-powered Qld Railways DL loco (some photos in my album) which is nearly complete but has had some reliability issues during testing so is currently having a heart transplant.
Hope you find what you need for your 1831.
Geoff P.