Bill some time ago I registered an old bedford bus in SA.
When I transferred the rego over from Vic to SA I had to get a policeman to verify the engine number ....... that's all!
Reason being that it was over 25 years old and therefore didn't need any compliance inspection. I'd pop into your local police station and have a chat to the old sarg on duty.
Just ask him theoretical questions in regards to procedure for vehicles the age of yours.
I'm guessing the original registration has expired?
Perhaps contact the Heavy Vehicle restoration mob & see if they have some suggestions as well.
http://www.hcvc.com.au/forum/YaBB.pl
Might be cheaper to join the club first.
http://www.hcvc.com.au/
Don't give up......... there's more than one way to beat 'em.