Monaro not monero
Try HSV GTS coupe
HSV Clubsport R8
VZ Monaro
Any september 2002 - july 2006 holden VY-VZ commodore or HSV Y or Z series front ends will fit as long as you get the corosponding headlights as some are different shapes.
And depending on headlight shape, you'll need the guards to suit too.
Your GTO shares our GTS coupe / monaro lights with the round ends where the VY-VZ's and most HSV's Y and Z series have the sharp angle lights like the clubsport R8 above and your 2004 to 2006 chevrolet lumina SS
Do a whole heap of searching around on ebay.com.au or
www.holmart.com.au and your bound to find a front end that not many have over there.
I hope thats not too much to take in. If you have any questions please ask and ill try to help as much as i can
If you want a front end that requires the sharp angled headlights then i suggest that you source guards and lights off the corosponding Lumina over your way as they will bolt directly on.