Any SKSs you typically run across have a milled receiver. Some Chinese barrels are pinned, some are not. There is no proof that pinned is inferior to the screwed on ones.
I own Chinese, Yugo (both M59 and M59/66), Soviet and had a Romanian. All functioned well, and all shoot decent groups for a military carbine. My Chinese is the best shooter with a screwed in barrel and stamped trigger guard assembly. Second is my Yugo M59 (no launcher). MY beautiful Soviet refurb is the worst shooter of the lot, yet all still hit about 4" at 100 yards.
Bottom line for me anyway is: buy the condition of the carbine, not necessarily the country of origin. They are a lot of fun for not too much money.