I'm not going to comment on the "legal" issues but let me tell you from experience;
1) Working on an SKS project gun is loads of fun (really) but it will take time, money and a lot of mixing and matching (a Dremel tool should be accessory #1 you purchase.
2) Don't count on anything you buy through the mail actually fitting/working on YOUR gun. I have rebuilt three SKS rifles from "U-fix-ums" (2-Roms.& 1-chi.) I have worked with stocks, gas tubes, trigger groups, magazines, sights, muzzle brakes, bolts & carriers, pins, springs, slings and finishes. NOTHING will "drop-in" except the charges to your credit card.
Most of the "Evil Features" won't improve the basic soundness of the rifle anyway. Think about things like length of pull (stock), trigger work, using the charger clips, headspace, finishes and rattles.