Well, at first look, could be a good idea, but I agree with Matthew about the lack of maps to put them on.
By now, the Eastern Front maps are all about laaaate war, so the KV-1s does the job. Even the new maps coming with 2.52, the earliest map is probably in 1943, when those beasts were dwindling in numbers.
About the KV-2, the scenario is even worse, cause it was used only in 1941, and mainly on the Baltic States and Leningrad, which will not be depicted, at least in the near future.
So, IMHO, right now, it would be a waste of efforts. If we need some new types, you could think about 3 big players in the late Eastern Front: SU-85, ISU-122 and ISU-152.
Best regards.