OK, would you take a 15k ton cruiser killer armed with 9.2" guns? Also, forbidden in treaties from '21 to '39. Cruisers needed to be 8" or smaller guns/10k tons std or less; Battleship between 17.5k and 35k tons and 10" to 14" guns with some grandfathering.
Australia doesn't need battleships of 72,000 t displacement; waaay out of context... Dunno why that was even mentioned! Not sure what you are specifying I do here, but hypothetically, Cockatoo could have built any contemporary British cruiser size warships in its yards and if it had to, I'm sure it could have, but in the context of what Australia feels it needs.