Given the locality and the fact that the white anterior edge of the labial scales appear to cover less than one third of each scale, this could be Austrelaps superbus?
Agreed, if the site was in East Gippsland you might id this as the Lowland Copperhead (superbus). There appear to be no confirmed records of superbus in NSW but given their occurrence to near the NSW border near Mallacootah in East Gippsland (Robertson and Coventry 2019) worth keeping a lookout for their occurrence in NSW.