Presumably you arrive at domestic terminal at SYD; bus to international terminal leaves every 20 min (10 at peak times) and takes 10 min. Walk in terminal is 5 min at each end. Worst case 40 min for the inter-terminal transfer. That leaves 50 min for getting through passport control and the security check; normally it takes 5 min but SYD can be busy so it might take 30. Comfortable connection providing plane ex-BNE is on time (likely to be the case for first flight of the day, barring bad weather). Also QF does operate BNE-AKL and might reroute you that way if the BNE-SYD departure is delayed.