Here's a quote about Sunbury from a quick google search.
BRIAN May laughs when reminded of Queen's 1974 debut show in Australia - the band's first outside England which caused a near riot at the Sunbury Rock Festival, outside Melbourne. Queen, particularly Freddie, were booed and abused by a yobbo crowd apparently outraged that "a bunch of English poofs" should top the bill over Australian acts including Billy Thorpe.
"It was all just a series of misunderstandings," says May. "Queen were unknowns and we never expected top billing. We were supposed to go on as the sun was setting so we could use our lighting equipment but we had to wait a while (the schedule had failed to account for daylight saving). The Australian stage crew didn't like this and started fighting with our stage crew."
and from QueenConcerts.com
02.02.1974 - Concert: Queen in private farm,
Venue private farm
Video recording Professional recording is rumoured to exist in archives of a local TV station.