You'll find that alot of ae85s were grey imported pre '91 before the old green plate low volume import scheme came in (pre sevs), like my old car. Back then cars were properly privately imported (i.e. no compliance or plate on the firewall), but unlike now there was no period of ownership of the car in another country required.
Back in those days grey imports came into the country in a much lower volume, so proper pre '91 imported Japanese cars are quite rare, particularly in the eastern states (they're semi-common in WA etc., probably due to a lack of official dealer networks around at the time). The good thing about these cars too is that they only have to comply with a very minimal set of adrs (mine was proper Jap spec, no side intrusion bars or anything), allowing for a greater field of aftermarket modification.
The easiest way of picking one of these cars is no compliance plate, and some sort of original pre '91 paperwork (i.e. the car's first rego papers) stating that the car is a private import and exempt from adrs.