Your receiver was serialized about December, 1943; the barrel is most likely original. They made a LOT of 9-43 RA barrels and they are seen on a large number of later M1903A3s.

A correct stock would be a "straight" stock (the shape of the small of the stock, that is) with an FJA and RA stamp, as well as a ordnance "wheel" (actually an ordnance "belt").

A Scant (semi-pistol grip) or Type C stock would be a replacement on any M1903A3. They were used as original on M1903A4 sniper rifles.