The Norinco SKS as imported in it original configuration has 14 imported parts as named by the BATF removal of any one of these compliant parts put your rifle out of compliance. These are the imported parts that apply to the 10 rd. fixed magazine SKS rifle,you will notice there are 15 parts on the list Part #3 is the Muzzle attachment on the Yugoslavian M59/66 A1 rifles it's the only 10 rd . fix mag SKS that has 15 compliant parts.
To make the Chinese SKS compliant once one of the original imported parts is remove you them have to remove enough additional imported parts so the rifle only has 10 or less of the original imported parts on the list still remaining on the rifle. Since the 10 rd. fixed mag has been replaced with a detachable mag which counts a 2 parts #14 and #15 you will need to remove two additional imported parts and replace them with 2 US MADE parts. Since you already have the mag covered parts #6,8,9,10,12 & 13 will be the parts your most interested in replacing. Or you can find and replace the original 10 rd. fixed mag. which will put the rifle back to it's original imported configuration.
The thing to remember is the parts count only applies to parts remove and replace off the list removing or adding a part that is not on the list has no bearing on compliance ie such as your dust cover scope mount,it's not a compliant part.
3. Muzzle attachment.
5. Bolt carrier.
6. Gas piston.
7. Trigger housing.
14. Magazine body.
If the Chinese SKS was imported before the 89 'nonsporting rifle' ban (after which the bayo was removed) and you have the original sales receipt showing the date of purchase before the ban then you can legally put a bayo back on the rifle or if the original owner has the bayo and took it off you can put it back on other wise you can't legally put a bayo back on the rifle without knowing it's history.