KV-1 was used until 1943, later KV-1S and KV-85 until 1944. (A small amount of the KV-1S and KV-85 continued to be used in 1945). not a doctrine t-34-85 sounds better, KV-1 bad it needs some love.
The Finns destroyed some of these
KV-1 in the summer 1944.
KV-1 is bad and it can be so. Therefore it could be placed in tier 4 without problems for the balance of the game, and for historical reasons. KV-1 should be the big and not so good heavy tank, which absorbs damage. The Sovjets have better tanks.