From memory you should be able to remove the barrel from your original lock . Take a real close look at the old lock unit ,and there should be a very small hole in the barrel . If you insert a piece of fine wire or a small nail ,you will feel a spring ?. Push it in ,and the  old barrel should pop out ??? Maybe some WD40 or oil will help as well .You can then reinstall into new bezel and use the stock key . Who said us Aussies were dumb ??

Regards Lon