the TTMRA only allows conversion of licenses. You cannot exchange your subjects in the hope of then getting the australian license. Any flight test in NZ will cos you mega bucks. best idea is to go and do the ATPL course in Mooloolaba. It is a full time course and by all accounts is top notch. It will save you a small fortune, and at the same time having a holiday.
There was some talk in Aussie recently about having to do flight tests for the issue of ATPL licences, you might want to check up on this before going over.