I had a dust cover mounted scope on my norinco SKS for years. It worked ok once I figured out that I didnt need to take the dust cover off every time I cleaned the rifle. I just squirted a bunch of CLP inside the dust cover and let it drain while I cleaned the bore and gas system! I did a full cleaning one every 1000 rounds or so...then re-zeroed my scope
I have had the rifle for 20 years w/o any ill effects from my neglect.
Last year I upgraded to tech-sight's and would never go back to a scope for my sks. The range I normally shoot at has the backstop at 120 yards. I can line up clay pidgins along the backstop and pick them off all day long with my SKS in its current configuration. That is more than accurate enough for me.