Dont believe that, if you ever see that service routing as a 330.
They changed it on me, had hotel bookings, so had to accept the swapped 737.
Wanted the last (my last hurrah on the 330 before they retire it), had paid for J, and then got the dreaded email, sorry, you are on the 737, not in those words, but similar.
Also, my PER - SYD, for Jan 2027, I had booked to try the 787, then they swap, I changed it to a 330, and then they now have put in a 321neo onto my flight.
Even QF9/QF10, with the 787, they can swap it, or put you onto a 737 to connect with the 787 at PER to SIN, or if the Iran situation has settled by then, they might fly PER -> LHR direct.
With them now putting lots of the 220./321neo etc, I dont hold a lot of hope for getting the 330 (maybe 1% chance they would keep it).
Am now going to use AirNZ for my flights, yes, I know they can change the 787 to a 777, but at least its still a wide body.
As there isnt a premY on their planes, most likely, you will seated in Y, unless they upgrade you to a subbed 737 J
If that plane you are looking at is the leased AY, then that one has a premY, but not sure if its the one doing your 07 May hopeful.
QF 330s, do not have premY cabins.
Ah, Just had look, yep, looks like its the AY leased 330.