Ian,
I'm no expert on the certification process in Qld/ACT, but if you are able to obtain a copy of the engineer's report from the previous registration, you might find it is acceptable in NSW.
Do a search on the
RTA website for "ECS", and you'll find the list of VCCS (Vehicle Compliance Cert., document vbi58.pdf) and ECS (Engineering Certification Scheme vsi15.pdf) approved engineers. The latter has entries for engineers all around Australia.
You'll still need to do the AUVIS blue-slip, of course. If you wind up having to get the thing re-certified, expect to pay $300-400 for the privilege. Consulmotive in Peakhurst (02 9153 0011) have a pretty good reputation.
cheers
RET