Did a lot of 1949 parts typically get “scrubbed” and replaced during the refurbishment process?
It's more likely case by case. However, you can generally tell if parts are period correct.
Right, scrubbing and restamping parts was just a common procedure during refurbishment within the Soviet arms (and equipment) refurbishment arsenal system, regardless of the year of the SKS. So many parts on 1949 Tulas are unique to that year, as pcke points out, such that you can look for those period correct features: spike bayonet, proper stock, proper ferrule, bayonet lug, receiver cover latch with loop, magazine without a pin (lost on this one), general bolt shape, spring loaded firing pin...