Get over to the SKS Survivors Board. Some extensive replies on such. For some reason the link below isn't sticking. You can find it in scopes and optics threads
Mounting a scope rail to the SKS receiver cover (Instructions: How To)
In general, the receiver cover mount don't hold zero well, unless you remove the cover latch pin, and tap a 1/4-20 through the receiver AND cover mount, while IN PLACE, clear through the other side. Install 1/4-20 grade 8, cut to size, blue. Many swear by this method.
The down side is of course you've permanently done something to your gun, but you can replace the stock pin.
I don't like the looks or eye relief of the scout type mounts.
PAX