Muz,
The info that I provided is not applicable to Imports as such but more specifically Individually Constructed vehciles. You should be aware though that the ADR for 079/01 does not start until 01/01/2005 so I don't see why there should be a problem with your vehicle???
Have a look at this website that has the details http://www.infrastructure.gov.au/roads/env...t/emission.aspx
Cheers
Paul
P.S. ADR's are national as you said but I cannot confirm the relaxation in emission standards across all states.