Well you will have a long wait, as I know nothing about Qantas.
Some people say I know nothing about anything, just ignore them.
The longest commercial flight with a B767 that I am aware of, is the one we used to do back in 1992-1993, Hanoi to Moscow direct.
We were the ONLY twin at the time that could do it, before the B777 and A330 of course.
