Man, this is your lucky day.
The problem with Aussie Vinyl (like on a Kingswood) is it's the wrong grain. If you want the corect stuff, you really have to get it from the USA.
Having said that, a friend of mine bought some vinyl for the roof of a Pontiac Grand Prix he used to own. He sold the car and never got around to doing the roof so he stil has the vinyl. This is the correct fine grain GM USA stuff. Give him a call. I checked with him first and he is happy to sell it. His name is Neil and his number is 0419-557-148. He's in Melbourne and is a good bloke.
Failing that, SMS Auto Fabrics in the USA is the only real option that I know of. They'll ship the stuff to you and are a good bunch to deal with.
Cheers,
Dale.