BRNO ZKK rifles actions come in three sized: short, standard and magnum. The ZKK 600 is the medium or standard length (.30-'06) action, the ZKK 601 is the small (.243, .308) short length action, and the ZKK 602 accommodates the long Magnum cartridges (.300 H&H, .375 H&H).

I'm not sure about the dates of the pop-up sights. The .375 H&H I bought in 1970 had one, but I recently had one added to a ZKK 600 action. The big negative factor about the action is the safety, which works backward for those of us accustomed to Model 70 Winchesters. However, a Model 70 type three position bolt shroud safety is available for it from several suppliers.