I doubt that car can be imported into Australia given the amount of mods on it, unless someone's willing to convert it back to stock to comply it and then bolt the mods back on.
Realistically speaking there's far better GTRs in Aus and Japan available, especially for the price, as you'll be paying American Wank Factor Tax (similar to Takumi Tax on AE86's) and Australian Import Taxes and Duties.
Also Canoodlians can only import cars that are 15 years or older, which means that GTR might be a bit hit or miss.