Unit descriptions in this game are somehow totally off some of the time and refer to older versions.
The KV-2 is no IS-2 and relies heavily on support. It is only available in soviet industry which IMO is no good choice in 1v1 anyways. In team games a well played KV-2 can be annyoing as hell.
I don't think it would be a good idea.
Your proposal reads like a M36 Jackson with a PaK43 and the armour of a King Tiger. That would somehow be a bit OP.
In CoH it's either very fast and therefore weak armour (Jackson) or rather slow and big armour (Elefant, Jagdtiger). It's not always black and white as seen in the Panther which has a good speed and a good armour but not the best of both either.
Conscripts on Vet 3 with triple molotov range bulletin on top of Hill 331 could theoretically throw a molo right to the Axis base acting as a mortar halftrack