One way to identify groups that may have enjoyed success in this area would be to look at the reported outcomes of government programs offering funding support.
The (former) Queensland Community Memorials Restoration was described as follows
> The scope of activity also includes cemetery reclamation and preservation projects, and assistance for local government and community groups to undertake projects to research, document, reinstate, and restore cemeteries.
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> The program also encourages clearing and marking older remote cemeteries that are closed, and assists communities to create digitised cemetery records.
A link on that page leads to a list of local communities that have received support. You could then look into the local papers of those towns for possible contacts for more information.
You should also be aware of the National Trust (NSW) cemtery conservation guide