From what I have found on the net tonight, the new school will evaluate the child's circumstances/education to make the best possible placement. The old school will provide a Student Data Transfer Note to the new school.
So from what I can gather from what I've read, they will look into where he's at with education, and see if he can go into the same grade he was in nsw, or if he'll need to go down.
This all changed in 2006.