I'll look in my parts bin tomorrow. I used to do work on 870's and may still have some pins. If I find one, I'll just let you have it as I don't do gunsmithing anymore.
I have a pin. Call or text 317-565-9068. You can pick up in Noblesville. My computer is tango uniform, so down to using my wife's phone. Had trouble logging in as it was automatic on cpu. Couldn't remember login.