Good old Trove - here's the reference to the record flight: 2hrs 23mins Adelaide to Sydney... with a 70 mph tail wind!
From The Canberra Times, August 6th 1950 ( I was one of the 20 passengers - a tender 9 years old!)
Record Adelaide-Sydney Flight
SYDNEY
Two former war pilots chopped three minutes off the Adelaide-Sydney flightrecord in a T.A.A. Convair today. They covered the 780 miles in 2 hours 23 minutes in the "James Cook" airliner with 20 passengers on board. The pilots are Captain Ken Fox, 30, of Kirribilli, and First-Officer Peter Pascoe, 29, of Stanmore. The aircraft was assisted by a 70 m.p.h.tail wind. The average speed was 335 miles an hour, at 17,000 feet.