Depends on your age. Most Aus general insurers GIO, SGIO, HBF, RAC etc have strict guidelines when in comes to imported vehicles. especially if your under age. If you are insuring a skyline and you are under 26 you may find it difficult to get a good premium, even more so if you have driving convictions or have lost your license made claims/accidents
With most insureres you have to disclose your convictions/claims/accidents within the last 3-5 years.
Ps. It helps to have someone listed on your policy as a regular driver who has a clean record and is over 26 if your under 26