Did you try the CASA website?
You can download the complete Australian Aircraft Register (as a .csv or excel file) and search/sort for any information you desire.
There was no such thing as the www when I was starting out. But there were microfiche machines. All Flight Service Units / ATC Centers had an aircraft register, mostly on microfiche, but sometimes on paper.
If I found myself in a place with a FSU, I would drop in for a cuppa and a chat and a loan of the Microfiche, and takes lots of notes!