As long as you have the right to work in Australia, the selection process won't go against you. I'll resist the urge to say, living in the states might lower your IQ and go against you... oops
Seriously though. It's been said in this thread and the NATS and Eurocontrol threads, either you've got it or you haven't. ECC and I are both in our mid 40s and start training next year, ask23 is in his 50s and also starts training next year. In the US, and some other countries, we wouldn't get a look in. If you've got what it takes here, then you've got a chance.
Go for it.