Very cool...and of particular interest to me due to the serial.
I am still trying to determine if my 49/50 project is a 49 or 50....yours shares all the most of the same features, and Ю is the second to last letter in the cyrrilic alphabet. Mine is an EO...if the natural progression follows the order EO should come before EЮ....all those early features (might) punt me closer to 49 again. The crossover from late 49 to late 50 is the most fascinating section of Russian SKS collecting IMO.
I didn't get a great look at your receiver cover, but it appears to have the hand struck Tula star and date rather than the machine stamping they got later on in 50...those are more associated with the later 50s with the 45 degree gas block.
I believe that is the second version of the looped takedown lever too...which is a little less robust than the first, and didn't last long before being replaced with a couple different versions of the levers we are all used to in later SKSs. That is a pretty cool takedown lever, they are pretty uncommon due to the short lived nature of that version. I have only known of the difference for a couple months...this is the first I have seen outside of the first example seen in a post here. Doh! redacted.
Does anyone have any idea what YEYOO means? I searched and got zilch.
Nice score!!