The GT40 heads production was discontinued in the USA years ago and GT40 heads are replaced by GT40P & GT40X heads... GT40 heads were only fitted to EB GT & EL GT in Australia. The GT40P heads were a standard on all AU Series I & II (Not Sure about Series III) XR8's & The T series cars + and they will requier different extractors. As were to get them brand new I am not sure if there is any performance shop that sells them.
As for the AU throttle bodies ring ford unless you want a bigger performance Throttle body in which case you should ring a performance shop near you.
You can get the GT40P's from Herrod Motorsport, apparently they still had 3 set's left last week. You need Pacemaker of Genie extractors and 90 degree spark plug leads to fit them to an E-series falcon.