I think that the best option for you would be to go and get your Australian ATPL. Simple solution. For, as I understand it, one of the
minimum requirements as listed on the Qantas website is:
Hold Credits for all Australian Airline Transport Pilot (Aeroplane) Licence theory subjects
reddo & Busta - As much as I can congratulate you on gaining your JAR ATPL, it doesn't seem to be what Qantas are looking for - otherwise I'd imagine that they'd add a disclaimer along the lines of "or other ICAO member state equivalent" to the above listed pre requisite qualification.
If guys & girls can get through with converted overseas quals, then I guess they are fortunate. Remember though, that airlines like Qantas have minimum requirements to screen the number of applications they receive. If you don't meet the min requirements as listed, then you don't really give yourself a fighting chance against all of the others that do...
And that seems a bit foolish to me...