Thanks to Ian who sent in all the frequencies below.
Those marked * have been confirmed!

National Parks Gippsland: 71.615MHz
National Parks Service: 71.660MHz
Lands Dept. : 74.420MHz

Unconfirmed Australian Customs Frequencies
(Tullamaine & Docklands areas)

489.475 - ch17?
489.500 - ch18?
489.525 - ch19?
489.550 - "delta base" + investigations/surveillance*
489.600 - *
489.625 - Docklands, surveillance of passenger/crew movements*
489.650 - Registration Checks*

Other Misc Customs frequencies: 489.675, 489.700, 489.725, 489.750, 489.775, 489.800

Locations of Customs offices:
Melbourne, Geelong, Portland + an observer at Pt. Lonsdale and Gabo Island.