Private imports are "complied" differently, as are cars older than 12/88 which are eligable for import under the "15 year" rulings.
It may have changed since I brought my S13 in under the private import scheme, Il ask the compliancer next door. When mine was done Green (Pink now) compliance plates are only issued to low volume grey imports, not private nor "15 year" imports. They are issued a VIN and are registerable with an engineers certificate indicating that the requirements have been met for registration.
Mine was around 6 years ago... my mates 32 was 3 years ago. The engineers certificates are not required to be kept in the car etc as per ones for modifications, they are held at the RTA.