I'm not sure of the regulations in your area, but in MS, the SKS will allow for a lot of options in terms of configuration. You will of course have to mind the feds' 922 regulations if you start reconfiguring an SKS; basically if you make changes, you will probably need to replace some foreign-made parts with U.S.-made parts. Tapco sells a "compliance kit", might be good to look it over if you are planning changes: TAPCO - Section 922r Compliance TAPCO® INTRAFUSE®
My SKS is sitting in a tapco collapsing stock with some tapco internal parts and magazines presently, but it performs well in the other stock as well. Many people STRONGLY prefer the original, tried-and-true, configuration.