There are actually quite a few details that show it's been through overhaul/rebuild. Chances are it was pulled from service like so many of the low number rifles were and sold. The barrels weren't changed when going to the 06 cartridge from the 03, they were set back, (re-shouldered and screwed in another turn), so your barrel is a replacement from the original (s) being worn out.
Items that I could see from the photos:
Rear sight assembly (knobs, and staff are too new, no 2850 notch)
Entire bolt assemblt (it's all A3)
Mag cutoff (should be serrified)
Trigger (should be the smooth sharp tipped)
Of course you already noted the stacking swivel and stock, I'm inclined to say WW2 rebuild, but I wouldn't think the rifle would have been kept in service that long.

---------- Post added at 10:13 PM ---------- Previous post was at 10:10 PM ----------

Nice rifle by the way!