The majority of flights use the track system going across the Atlantic, if you look up ETOPS coverage it entirely covers the Atlantic using the 180 min rule. So any twin jet airliner can use whatever track sytem is in use that day along with any 4 engined airliner provided it meets ETOPS requirements. I have never done a non ETOPS flight across the Atlantic, not sure how much more time it would take using 60 min s/e from an adequate airport. (maybe someone else can help you on that). Part of the reason a 747's flight time is generally less than a 767 is cruise speed, they usually blow by us at Mach.84 or more while we're plodding along at .80 or .82