As far as what parts are original Australian... my guess is just the receiver and perhaps the bolt. I believe they ground off the original serial number on the bolt so it may be hard to tell one way or the other. Otherwise look for markings with OA, MA, BA OR A inside a star to indicate Australian parts. If it Is in its original military configuration you may see these marks on the sight protector, barrel band and nose cap. The bsa FTR’d rifles I have had almost all those mentioned parts replaced with bsa manufactured ones. Sorry not sure if that really helps you much... need more pictures.