Putting together a Stevens Marksman-12 and I'm old and can't use the standard Marksman sights and wondered if there was a Lyman type rear sight I could use. I do have a an old adjustable no-name tang sight I think I can make a mount that will go on the narrow metal section that fits in the stock. Is there a Lyman adjustable receiver mounted rear sight that might work on the Stevens Marksman and not block the hammer? This is not meant to be a collector or anything -- Just another little single shot for my Old Man's backyard target range. 

Thanks for any help,
Boomer

I was able to grab an adapter that attaches to the rear scope block that allows me to use a redfield receiver sight without actually drilling and tapping the receiver. CPA has an adapter on their website that allows you to use an anschutz rear sight. Not exactly pretty, but it works good

I don’t know what the base is but can see if there’s a name on it. I would bet someone on here knows what they are.   When I bought the gun it had all kinds of issues, including a messed up chamber and I had to install a liner to fix that.  A sears scope came on it but the elevation adjustment plastic mount broke, so I replaced it with this one, which is a Weaver.  The Weaver in not as sharp as I would like,  but even this way, the gun shoots really well.  So, I’m thinking about putting the Lyman 438 I’m rebuilding (shown in another thread) on this gun.  I would make a mount that would use the same holes that are already there because the Lyman uses different blocks.
Bob

Looks like Bob's base is just a Weaver rail for a round barrel. A Thompson Contender uses the round bottom base and should work.

I ue a 3/8" dovetail base which allows me to mount a scope or use an Anschutz rear sight.