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I would guess they are available. I have been provided PJ's on a day flight many times from BOM-SIN, no issues.
As Flashware suggests, if they are not handing them out, just politely ask and most likely you will receive a pair. I woudl find it hard pressed to think a pair of PJ's is breaking QF's balance sheet when you are paying good dollar for the seat. They may not actively hand them out but I bet they have pairs in the locker.
That was how I got my last pair. I was on QF009 MEL-SIN in J (connecting to QF005 SIN-FRA but that leg was in whY) and when I explained my overnight leg was going to be in whY and some PJ's would help, she laughed and handed me a pair
If not indicated then PJ's are unlikely to be distributed on the QF87 airbus.
I always ask for my PJs in J as soon as I board as I generally want to change into them immediately and the crew don't hand them out until you are in the air (unlike in F).