They fit into EF/EL falcons with a little bit of a shove so an AU shouldn't be much different there more or less the same size in the engine bay, maybe the height factor could be a thing but then leave the bonnet off and tidy up the engine bay.
Do you live in NZ? If you do you won't have any trouble registering it, as long as it is safe. It's something a bit different, but I don't know why you'd bother. There are plenty of decent cars a clevo could go into that would not only cost less, but look better than an AU.