Hi Steve,
So you have the model plate - there should be a compliance plate in there as well, which will give you the date of manufacture (All Aussie vehicles have them after 1972ish) and list which ADR's it needs to meet.
You've got the old WA Rego number there, and you've got the chassis number, so you might be able to get the registration history out of the system, which might help:
https://transact.ppsr.gov.au/ppsr/Q...si=4&wsi=0544a515-42a4-4140-b650-49ba1b739cf5
A quick check on the WA Department of Tranpsort Rego check gave me this:
View attachment 156725
The Chassis number on the frame should match the one on the plate... if it doesn't, then you've got some really big problems...
Hope that all helps a bit,
Ed