I love the music for RUS and was thinking adding more period music as I had added more Civil War music to AACW.
I found this on amazon and feel its perfect for this game!
(I think a few songs are the same)
"Best of the Red Army Choir"
http://www.amazon.com/Best-Red-Army-Choir/dp/B000066RMJ/ref=sr_1_6?s=music&ie=UTF8&qid=1305075285&sr=1-6