I would be interested to know what you find.
There should be several: anywhere where the components were built up remotely and then conveyed to the main line in sequence. Your list is pretty comprehensive. I would add, perhaps above the headliner, behind any quarter panel trim, inside the doors and/or above the fuel tank.
At the end of the line they were gathered up and thrown away along with all the other trash: extra screws, coffee cups, love notes, inspection tickets, etc. Any that were covered over were left in place.
Perhaps the guys at Holden were a little more rigorous about that then our dudes here domestically, making them harder to find.
I don't know what Eric had in mind. Probably needed one for his book: