Would you like to look at YWKS as "destination" then have a look at SkyVector.com for the intermediate waypoints and see if you can tie that in with the ping circles. Routes from the north towards YWKS all go through the ATSB amber arc.
If someone can produce the en-route winds for that date in a readable format it would then be possible to modify the reasonable cruise mach no (0.82?) for the ambient winds to generate a G/S.