Congrats on the purchase. A piece of history there.

Yup, the Mk II Ross rifles tend to really blow out the shoulders on brass.

The remains of a C-broad arrow Canadianicon military ownership mark is just visible just ahead of the buttplate on the right side, and the ghosts of the serial number are also visible on the buttstock. Try shining a 'black light' (UV-A lamp) on it. You might raise the contrast enough to read the serial. Markings will be in the format of

###
------- AA
####

Any remains of a U.S.-stamped 'flaming bomb' and serial # on the underside of the butt behind the trigger guard?