It's a nice, well set example.
But a better dating than 1965-80 is unlikely to be achieved. Although the base shows a lot of "wear", it seems to have more than would be expected from something less than 50 years old. It is possible that the "wear" was mostly the way it was originally finished.
Apart from the "experimental" weights of the final couple of years of Strathearn's paperweight making, I know of no way to determine a closer dating for their regular daily production weights.