We here, on this side of the ocaen are so not used to shipping to you. Who does and doesn't is a mystery to me and probably most here. Though you in good shape since theres a bunch of Aussie fellows here.
Keith Black sells a wide verity of Hyperutecic (Spelling as well!) pistons in dish flat top and domed. Check this link out;
http://kb-silvolite.com/index2.php
And then ask your local/national speed shop for them.