There are several receiver covers u can buy off of Ebay that will give u several options to mount your scope. Also there are several shell deflectors for your SKS that are easy to install in case you want to add a longer scope. Both items are inexpensive also. Hope this helps.
i bought a nice replacement dust cover with tri-rail simillar to this one at the Gonzalez gun show a couple weeks ago for $30. havent installed it yet, but it seems solid.
from the research ive done, the reciever/dust cover mounts are not very good because they don't hold zero. they move around too much. the scout scope mounts that was posted are the best way to go since they replace the original rear sight.
Best result that I have had over the years were all side mounts drilled and tapped to the receiver. The best was a Russian P/U mount, gunsmith installed, which mounted to the left side of the receiver. This allowed me to use the iron sights, reload using stripper clips, and remove the receiver cover. The second best I have used was the Choate side mount which is installed in the same manner and offers the same features, although removing the scope and mount with this one did not rezero as well as with the P/U design. Pic is the Choate mount installed from an example pic from an article on http://www.surplusrifle.com/reviews/choatesksscope/index.asp
You can get the ones with the screws that tighten to the receiver to hold zero,until you remove the feed cover for cleaning,at which point they will wander a bit.I personally have never had them re-zero properly when re-installed but others have had better luck.Really depends on what you expect from your rifle.No matter what you do you will never end up with a precision rifle when starting with an SKS. If you want the best chance of coming near that, you cannot expect any mount other than the side types to provide a rock solid base,with exception of the ones that replace the rear sight for a scout type setup.