unfortunately it's not as easy as ordering something like a new water pump. There are a slew of legal issues involved. Look for engine or half cut importers, probably most common in large port cities. Beyond that, especially in Australia, I can't help much.
At this point, why don't you just find a shop to do it for you? I'm all for helping out online but there are limits. When you want us to do the work for you for free because you don't want to pay someone to do it and you can't or won't yourself is one of them.
go on forums for cars with JZ engines and W gearboxes and browse through the for-sales. I don't know if they're exactly the same in AUS but several lexuses and supras with the parts you need can even be found in the junkyards.