These are very interesting rifles. The scopes and the bases look heavily influenced by the WWI SMLE sniping rifles. I heard there was no set standard for a WWI SMLE sniping rifle resulting in some incredibly rare and valuable arms. The Australian sniping rifles came in a high and low version. Looks like a hybrid of the German claw mount and combined with cam locks. How were the bases affixed to the rifle? I am guessing a combination of silver bearing solder and machine screws?
Definitely not a plug and play installation.