I don't know the history in detail, but have an idea any surviving examples were converted back to KV1s by 1942. The high profile can't have helped - doubt they were immune to 88s. Also, I'd guess they might have struggled to fire on the move?
A Panzer 4 Ausf D can't put a scratch on the tank. I did research the KV2's firepower, why didn't they make huge numbers like the T34, it was a assault gun and a heavy tank. Also it can crush the Tiger at 1942 or 1943 like a punch. I doubt it's tough enough for Henschel 129, especially the rear armor.