I am getting ready to put in an order myself, here are the part numbers I found... You should probably double check them with your local GM parts dealer though...
Oil Pan (pan, non magnetic plug, gasket and bolts) GM# 12581209
Oil Pan Gasket GM# 12558760
Magnetic Oil Pan plug GM# 23011420
GTO (Holden) Oil Pump Pickup GM# 12572654
GTO (Holden) Windage Tray GM# 12558189
GTO (Holden) Dipstick GM# 12562468
GTO (Holden) Dipstick Tube GM# 12561544