Was just talking to my brother who tells me if you had the Safety compliance plate (ADR) and the ute had a traceable past with state road authority,you would be able to get a reprint of the ID plate??, but thinks the reverse like you have will be difficult :( .I say don't spend a cent untill you seek advice from your road authority incase it can't be rego'd .
apart from that it was put together in Melbourne in 76.
Not all lost yet just baby steps for now !! Keep asking questions and some one will have an answer