Not sure what size receiver stamping these were made for. The Norincos use 1.5mm, so if the E.German was a 1mm it will likely be loose. Doesnt mean it cant be done, but youll probably have to build it up in spots with epoxy or shims. The tang will likely be a different shape/ length too. Also, the grip bolts and/or wedge nut may not be compatible- youll just have to try it and see.
Of course, all this assumes you dont have a slant-cut receiver. Slant-cut Norincos require special stocks that only fit them.
My biggest concern would be how brittle/unforgiving that 40-year old plastic is when trying to fit it. If the shoulder stock isnt fitted correctly, shock over time will induce cracking.
Also note that the Norinco lower front handguards had a metal spacer between the wood and the receiver which most other manufacturers dont use- this makes adapting all-wood or plastic lowers a pain.
Timbersmith makes excellent AK stocks and they sell kits specifically for Norincos. They aint cheap, but it may save you alot of time and effort since they will fit better and require less tinkering to get there. EDIT: Hmmmm, I dont see them listed on their website anymore, ugh. I would probably still give them a call and see what they say.
Look into the Magpul Zhukov line of stocks too. Magpul makes top-quality products and their Customer Service is great. Call them too and see if they recommend a specific stock and/or hardware kit.
Bottom line- dont expect ANY stock to fit without some fitting. They just dont.