Hi there,
Do you have a copy or a transcript of the NSW BDM certificate for his death? A transcript will give you the details re the parentage of the deceased, also the occupation and age of the deceased (including surnames) , any marriages, spouse/s and children/ages of the marriage/s ... as well as cemetery details, clergy, funeral directors. Of course the family history information is only as reliable as the informant's own knowledge, but it frequently provides further clues to advance your searching.
NSW transcription agents appointed by the NSW BDM can provide transcripts cheaper and more quickly (email as pdf attachments for example) than the real deal certificates.
Cheers, JM