I collect some Czech Brno rifles, and I've wanted a ZKK602 in the original .375 H&H and with the pop up peep for some time, but they're not usually offered for sale by those who have them. I'd say yours is worth about the same $ as the current CZ500. The 602 was made in the early years with a pop up peep sight, This one does not seem to have been so equipped, so no premium there. The re-chamber would be attractive to some buyers, certainly not to me. They were a bit higher quality than the current CZ 500, but used condition vs new would even things out IMHO.