Peter,
At RChat, we are not allowed to name people who may be still living. There is every possibility that the person you are naming in your opening post and in your topic heading is still a living person, alive in Australia. Whether you are new to family history or otherwise, and new to RChat or otherwise, when you signed up to RChat you would have read the Terms and Conditions, and noticed that we are not to breach or request the breach of privacy of persons who are or may be living. And, on your NZ thread I am sure that various regular posters have been respectful of this.
But I assure you that the person noted on the New Zealand police gazette in the 1940s as an Australian, born 1920, is probably the same person listed on Australian Electoral Rolls in the 1950s, and in the 1960s and as recently as 1980. So simply put, he is NOT your late Dad who died in New Zealand in January 1979. Plus, there is every possibility that the chap you are naming, actually married in Western Australia in the 1950s, and stayed married to his wife - afterall there is a person matching the name of his wife who is found on those same electoral rolls at the same address as him, in Australia, particularly including in 1958 and 1963 and still there in 1980. He may well be the chap who died in Queensland in 2002, and alternatively there may be others of that name, born in the 1920s and who are alive at the present time.
Ryerson index is one of the online resources listed in the Resource section of the Australia Board, here:
https://www.rootschat.com/forum/australia-resources-offers/Here is a live link to its home page :
https://www.ryersonindex.org/ It is easily found via google.
This thread is found easily via google also, simply by searching for the name of the person named in your opening post.
I have searched through various offline resources in case I can help your quest to find further information about your late Dad, so that you can search for his parents or siblings and your family on his side. I have not yet met with success.
JM