The Ca. emission sticker is on the left down tube just below the steering head on my Ca. Ural. the biggest worry would be the mileage. If your seller was the one that bought it in Ca. ask him for a copy of the sales paper work showing that the taxes have been paid or you will get stuck for that too.
I think I would stay far away. The can on those is normally used to hold nitrogen that works with a diaphram to keep the oil from foaming inside the shock. The only air shocks I've seen were on my Son's HD bagger and were very close to what you see sold for cars and pickups.
My Denso has a Russian gear installed by a dealer here to match my Russian timing gears. Check with the dealer you are getting the Denso from otherwise I think the Ural set-up comes with a Herzog gear.