Lots of Australian ISPs route to Asia via the US. So it's a coinflip as to whether any particular customer will see much better pings, or much worse pings, if you host in Singapore/Tokyo.

I'm not sure about Perth, but from AWS Sydney I'm seeing pings of around 400ms to AWS Singapore.

People who understand these things a lot better than I do always tell me that pings aren't a reliable measure of network latency.