Things we know about.
1 - Spike bayonets were authorized until Feb. 2nd 1950 or if the supply of spike bayonets expired before this date
2 - This rifle because of the stock ferrule shows that it was made for a spike bayonet.
3 - Eyelet latch pin has been found in 1949 and early 1950 SKS's.
Things that are in question.
1 - Are 45 degree gas ports found in 1949 SKS's?
2 - Is the serial number - ИM found in 1949 and / or 1950 production?
3 - Does the single line serial number on the cover mean anything? My other 50(EM 717 has 2 lines).
4 - Why would they replace the 90 degree gas port with a 45? They would have to remove front sight to get to gas port.
I have taken some more pictures of the gas port and the cover. You can see the vertical machine marks on cover.
https://ibb.co/album/tmPggz