I don't believe there's anything in Aus comparable to EC/UK261. Qantas are also not likely to create F award space for you to try and find another potential route (i.e. one of their other Eastern origin points to the US) in this instance. Having to deal with both BAEC and QF for this flight will make changing things fairly difficult (except to get a refund).

I would expect you'd get the difference between F and J Avios offered back and not much else unfortunately.