Reward?! first you need to find seats, but the reduced rate of SC earn (assuming you are PC or PC+) means you'd need a number, and quite a bit, of trips to get to 360 - with the associated charges, you may be better off to do a SC run like MEL-SYD-OOL in J (which would get 320 SC with DSC) or say MEL-BNE-CNS/TSV in a mix of J and Y which could earn 360 exactly) for yes, a bit of an outlay, but given the reward SC earn is reduced for dom and trans-tas SC, you'd need more travel than that, assuming you can find it right now, to earn the 180 pre SC to earn.
for example, a MEL/SYD-PER transcon in J would arn 38 SC one way, so you'd need about 3 of those return to make your 180. Or, MEL/SYD/BNE/ADL-NZ in J earns 32 SC in J, so again you'd need 3 return reward flights to earn enough pre DSC to earn 360.
even if you get creative like MEL-SYD-BNE-PER or something, you'd still need quite a bit of effort to do it with reward seats.