I have done a few trips with gear – and am NO expert! There have been quite a few topics on these forums also. Have a search...
Anyway, whether you can or can't (specifically on Qantas) depends on lots of things like the plane, how full it is, the time of day, the width of your polite smile, the side of the bed the check-in person got out of etc etc. Some Qantas flights use those big aluminium luggage crates, that are pre-packed and loaded on to the plane. Your gear will not fit in one of these. On one flight, I have been told my masts and sails wouldn't fit because of the angle at which they needed to go through the door

They let them on in the end when the tears welled and I sniffled a little

I have been asked by Qantas to take my gear to Australian Air Express (twice) - who wanted about as much money as my ticket cost and couldn't guarantee which flight it would go on…
With Virgin, I have never had a problem, turn up, say "this is sporting equipment". Away you go... Virgin have only one type of plane (737 - 700s and 800s) and they are all hand loaded.
Worst case scenario - freight your kit to someone in WA, then pick it up from them when you get here...