I would contact Parkes Council not just their Library, but the staff responsible for the cemeteries

Their website says they are responsible for .... genealogy enquiries ...
If you have a copy of the death cert, or of the official transcription, then attach a copy to your enquiry as the info on it should help them locate the relevant burial records.
The live link I gave in my earlier post should lead you to :
Cemetery Reservation Process & Interment Process
The following pages detail the cemetery reservation and interment process in the Parkes Shire, as well as providing some details on the cemeteries themselves.
Online access to Parkes Shire Council Cemetery records is available through the Australian Cemetery Index.
Cemetery Reservation Process
Cemetery Interment Process
But I am suggesting that you need to seek out where the Cemetery's burial register is located as that should give you a detailed location within the cemetery, far more detailed than the d.c. info.
https://www.parkes.nsw.gov.au/your-council/contact-council/contact-information/ So perhaps start with an email enquiry to that address, asking for the email address of the person responsible for the Goobang Cemetery burial register

Even if there was a headstone, it is possible it has fallen or been removed. The burial register should give plot and row and section (or similar headings) at time of the actual interment, and not just when a headstone is delivered from the stonemason weeks/months or more later.
JM