I agree, a very nice example, about as nice as I have seen on the forums. The bolt is especially intriguing, do some pictures of the markings, especially under the handle, it is difficult to find an unaltered (bright metal) Polish bolt and I have not been able to document many, those I have recorded often are German in origin, or have the typical Polish markings (odd characters, accountability or fit markings) or on occasion the FB (Radom) shield marking.
As for the markings, I hate to suggest this but you really should take this to Gunboards Mauser forum, John Wall is often the best person for these kinds of questions. He has in the past given the best answers to these types of questions and he doesn't frequent here enough to see this thread. The "Z" represents ordnance depots or something along those lines, "zbrojovnia" (spelling on the forums varies) but the exact purpose of the various styles this marking comes in isn't clear, at least to me. You can find it in different styles, locations, and apparently used for different purposes or maybe represent different facilities.
The other markings, the "K" in a shield of sorts is common on stocks, different locations but I do not know the meaning and no forum posts or articles I have on file record a purpose. Other than regurgitating previous posts by John Wall, many of them nearly 10 years old, I can't add much to this topic; - John Wall is the only collector that is both knowledgeable and forthcoming when it comes to Polish rifles on the forums. Whether it is because no one knows much or whether those that do are secretive with their knowledge, I am not sure, but of the dozen or more posts I have saved over the last 10-15 years, he is the only one that answers questions or contributes information of any value.
I would take this topic to TP's and JohnS forum for answers, but please do post more pictures of the rifle if you can here. I have a rather large database on Polish rifles, their economy and industry but have never trended production, - but intend too one day, it seems to be a wide open field for study, hardly no one knows, or will share their knowledge about these very interesting rifles. I assume some of the problem is that so few rifles exist in the condition of your rifle...