AK's OK

The ribbed cover came out in or around 1952, for the AKM. It can be used on the AK-47, no problem.

The magazines interchange back and forth, meaning the ribbed or or non-ribbed magazines. The "slab side" mags were felt to be less reliable than they liked, so the ribbed model was made. The slab sides would be less likely, but it's entirely possible.

I guess what I'm getting at is don't write off the Verlinden AK just because of the ribbed cover or its magazine. Look at the period you're modeling. A pre-1952 AK won't have the ribs. If only Chinese rifles are being used, it's less likely to have the ribs and a slab side mag, but neither is set in stone. If weapons were smuggled in from anywhere else, it's certainly possible.