Blimey Aidan, how far is not too far???
Where abouts in Australia are you? I have family and close FIAT friends on the East coast around Brisbane, QLD, who are always looking out for 131s for me - even though I'm in the UK
Whilst they are few and very far between they do exist.
When I was over last (about 3 years ago) I saw and took pics of a very tidy orange 1600 Special sedan, and when I was over the first time in 1991 (for my honeymoon) I saw a blue 2000TC SuperBrava.
My mate in Birkdale, QLD has a 1976 131 Panorama that he has dropped a 2000TC motor into and also fitted after market air con - not that he's likely to sell it - he's only had it 20 years
There are a few clubs in Aus that it might be worth contacting, dependant on where you are.
Are you choosy about what model sedan (2 or 4 door, early or late?) or will you take what there is?
Let us know and we'll see if we can help.
Cheers
Simon131