A response from the State Library of NSW, who conducted a most useful search for me.
"I searched for Milton McGuire in the NSW Probate index and he was not listed. I searched the Sydney Morning Herald for a death notice or funeral notice to see if family members were listed and I was not able to find an entry. I searched for 6 moths after Milton McGuire's death in legal notices and could not a notice relating to his estate.
The published probates online was searched and could not locate Milton McGuire.
https://onlineregistry.lawlink.nsw.gov.au/content/search-probate-notic...etcThe Supreme Court holds Probate Records from 1977 to present, the inventory of property is only available to executors, administrators, residual beneficiaries, and applicants who have commenced proceedings in contested family provision claims (case number must be advised).
Unfortunately I have been unable to locate the information you want."