Will,
So, there's really TWO rear sights available for that rifle.
One's the Receiver Peep sight, mounted on the left side of the Receiver by a single large screw (mine's blank, with just a hole there). This sight is an adjustable sight with a screw in Peep Aperture. It appears to be an "adequate" sight.
Then there's the Stevens #130 Tang Mounted Peep sight with "micrometer" adjustment. This is the one I'm really looking for.
What's there on my rifle now is another "period" Tang Mounted Peep sight of an unusual design. It in itself probably has some collector value, but as a shooting aid it leaves a lot to be desired. It has a nice screw elevation adjustment, along with a legible scale and Target Disk aperture. However, for the windage adjustment it uses a pair of opposing knobs (loosen one, tighten the other) that screw in tight against the sight's staff that contact the staff below a pin that the staff pivots on.
Thus adjusting for windage moves the staff in an arc, either left or right.
With this set up, any change in either windage OR elevation changes the other's setting, meaning that you have to constantly find the rifle's zero with any change in sight adjustment.