I know this rifle as a Zastava PAP and have one.
I ain't no gunsmith, so let me classify my remarks first with that. But as I understand the situation, it is indeed different than a Saiga conversion. It is something to do with the angle of the rear of the rifle ("slant-cut receiver" maybe?) which is NOT standard for Saigas nor other AKs. So it is NOT just a matter of taking off the included thumbhole stock, popping on a new one, and going. Because of this angle , new stocks don't 'properly' attached or should I say are not supported right. It was explained to me that while you physically COULD attached the stock, it would not at all be the same as attaching say a stock to a Saiga or even a normal M70, because of this lack of support.
I can't for the life of me remember the famous AK Stock producing company from California, somebody here knows who I'm talking about, anyway when I got the rifle I Called them and asked for a stock set. He basically said sorry I Can't in good faith sell you one because it's going to break, its not supported right, and I really don't want to be having to deal with "Hey your stock broke on my rifle!" when it is apparent it will indeed break.
Having said all of that, it is definitely done before, and I've seen some awesome examples, but it requires like real gunsmithing/ real tool use etc, you gotta get down and dirty and manufacture a little- it's not just bolting on a scope to a picatinny rail etc. And I actually was told and just saw a shining example on glocktalk, the best idea is actually to use an AK - to- AR/M4 stock conversion kit... that still requires some metal work but in the end hooks up much more stable-like and looks absolutely awesome.
hopefully some small part of what I just said made some sense to someone.