Unless you've been told otherwise don't assume that you'll be in an A320 for the selection sim. These sim checks are to test your instrument flying skills specifically and other flying tasks such as working in a basic crew, organisation etc. They are not to test your ability to fly the A320 per se.
If they are doing the assessment in Melbourne then my guess would be the 737 classic sim at Ansett. It isn't as busy as the other sims there, has fully conventional controls and round dials. Perfect for an assessment sim.