Don't you have one more segment in the country of origin? Meaning you can sneak down to ADL at the start to pick up some more SCs on your way to SYD. I think I remember that was tight on mileage when you were looking at a DCIR22 but shouldn't be a problem this time.

One other gag to be aware of is that on BOS-SFO American has started to run some 757s so you may want to choose your flights carefully there to make sure you get the 767s. If you are going to ANC anyway, you don't need to spend any more time on a 757.