Well, the odd thing with Australian releases is that, sometimes, they port over US releases as-is (in NTSC). However, since there have been at least a couple of PAL releases in the UK, a port of those is more likely.
Again, the PAL-speedup only applies if the episodes were mastered from the...
There's a good chance the Australian import could suffer from the PAL-speedup issue (where the soundtrack plays 4 percent too fast), if they transferred the episodes from film prints, rather than videotape masters.