This site is a constant work in progress. Hope you find it useful.
Identify by Skyline Angle
If your stamp is heavily cancelled and the only distinguishing feature is the skyline then possibly you can ID your stamp using this page. The angle of the skyline will align to certain places in the word AUST.
After finding and recording the positions of the closest matches, go back to the main menu and use the other pages to help you further refine the search.