So I ended up joining the NSW Historic Muscle Club.
The process was fairly straight forward all in all:
- Got a blue slip done for the XE
- signed up & paid membership to/for the club online and had a form sent to me
- filled out said form
- sent said form to the club along with my engineering papers, ID, car photos.
- In return they sent me a Historic vehicle form with the required signatures etc, which is technically the wrong form. But the RMS didn't seem to care.
- Took all this to the RMS with my old plates. De-registered my full rego and filled a few forms to move on to the classic vehicle scheme, got some plates and it was all done.
All up the process took about a week in total.