I have two different SKS scope mounts.
1) The 'tap-in' type, with the front prongs that must be carefully filed to fit the particular rifle. Once fitted, it is tight and secure, and will fit only that rifle well. On another rifle, it'll be loose and sloppy.
2) The 'set screw' type. Uses two setscrews on each side to lock it in place. Uses a narrow 'rimfire' style rail - needs a Weaver rail for better security.
The problem with a scoped SKS is that it will not appreciable improve accuracy. I does make it easier to see the target, but experience with the open sights is far better. A scope is just another thing to break.