If possible, have somebody on the forum, or somebody you know from that area, check the car out. Just to make sure the car physically exists and matches the photos. Do a PPSR check (national system). https://www.ppsr.gov.au/glossary/revs-checkDo a state records check. (Google 'registration check' and choose the applicable state). If you've done all of the above, and you're spending big bucks, then it's worth having an inspection done by the local state motoring association (NRMA, RACT, RACQ, etc).
Doing the above might cost a few bucks, but it potentially saves a lot of hassle later.
Note that some states -e.g. South Australia, from personal experience - sometimes never put the chassis / VIN numbers or the engine numbers on the registration papers.