That Stevens may need a couple holes added for the side mount scope. Not unusual for early versions not to have all the holes that the later ones shipped with. I had a Rem 721 like that wasn't drilled for scope mounts. The ones at the rear should be for a peep type sight. If you haven't tried one, they are easier to use than the barrel mounted sights. You could also have the top of the receiver drilled and tapped to take a standard mount of some sort, but keep in mind the path of the bolt handle. You may need to use higher rings than you think. For a plinker like that, I'd see about fitting a dot sight like the Bushnell TRS-25 to the front receiver ring or replace the rear sight assembly with a base for one. Rimfire Central forum has all the experts on these little rifles. Most of the folks are helpful.