Re: Hello from the outer suburbs of Antartica!
I don't know of anything that would not be prohibitively expensive, considering shipping from the U.S. You might be better off altering a frame and having it welded up for you. Same with the gas tank. No shipping involved. Good luck to you. It may be that one of the boys from Oz could help you find a frame. Shipping from there might not be too bad.
Someday when I grow up I will probably lose interest in toys with wheels, but until then...