Sorry - that's not how it works. As a S/O you will be assigned either A330 or B744 depending on Qantas' needs at the time and your total hours relative to others in your joining group.
As a S/O you cannot transfer to another aircraft type as a S/O except under unusual circumstances (eg a type phased out or an excess of S/O's on a type). This is not particularly fair given the pay and roster disparities, but it does save training costs.
Just an idea - but if you really want to live in NZ, perhaps you should think about a NZ based carrier.