Can you verify the dimensions to the nearest mm, and give a height to the nearest mm?
I have a number of rail profile details which might enable me to identify the weight.
However from the dimensions you have already given I would say it is 40 lb/ yd rail. That is the weight which was used on the "mainline" of the Powelltown tramway which ran from Yarra Junction. However I would have expected the base to be wider than 60mm for 40 lb rail, so it may be 30 lb. In that case it may have been used in sidings of the Powelltown tramway at Yarra Junction, or come from the earlier Gilderoy tramway, which also started at Yarra Junction and was powered by horses.
In any case it is too light to have been used on any Victorian Railways line. The VR 2 ft 6 in gauge lines used 60 lb/ yd rail.