Comparing the OP's rifle to a relatively close serial numbered rifle in Scott Duff's data sheet book, most of the parts shown in the photos are correct. I believe the barrel date is significantly too early for the serial number and the barrel's finish appears too good for the condition of the receiver. The op-rod was modified and there is a second P proof of the stock. To me, this all adds up to someone's attempt to correct an arsenal overhauled rifle. This is quite common. Based on this, I don't think there is any way to conclude any parts are original to the rifle.