The rear sight is the Mk3 type, with windage adjustment; so I'm pretty sure the barrel is also dating from the conversion.
RobD, good question about the buttstock; I really don't know. I wonder if I can find info about that in my Skennerton's book. And, I am thinking about getting a repro forend from EFD in the UK
; will cost me a lot, but it's the only place to find a "fat belly" forend, as opposed to the ones seen on Mk3* rifles... And I'm pretty sure finding an original is not possible.
Lou