That doesn't seem to work: the MCT at MEL from JQ to QF appears to be more than 70 minutes, and on May 18 (sorry, didn't specify that earlier) the JQ LST-MEL flight leaves at 3:20pm, arr MEL 4:20pm, with earliest 'legal' 'connection' to SYD at 6:00pm, arr 7:20pm, way too late to connect to QF3 which departs 7:45pm.