Huey,
It used to be that if you returned to Australia with an FAA ticket, providing you worked `commercially' on that licence in the USA for 200 hrs or more before returning to Australia, all you had to do was an air law exam and pass a flight test.
The `200 hr' proviso came in to effect after, during the 1970's, a lot of blokes whent over to do FAA licences as at the time getting an Aussie ticket could take all year to complete( two sittings a year, fail one subject and it could easily take you 12 months to get the theory subjects out of the way) The 200 hrs was meant to deter people going over to the USA to obtain their license (probably initiated by local flight schools missing out on business)
Contact your local CASA rep and get it from them direct.
Good Luck
M/V
p.s if you are a non-resident, for a `small' spotters fee I will locate you a bride