YSSY-KATL = 9285NM
B77L would make it no worries. You maybe slightly payload restricted from 45 tonnes. M0.84 cruise gives 16:45 mins direct (crossing the coast at Cabo San Lucas in Mexico) Return sector with headwinds is the problem. Last Christmas we flew YSSY-KJFK direct on the B77F with the Sheikhs horses. Not sure of how much gas. With the above KATL scenario, you could only load on 134.3T gas. Northern Hemisphere Winter east coast weather would also pose a problem. 207 ETOPS not a problem on that route.