If you know any cowboy action shooters, those guys will know who the lever gunsmiths are. They're always slicking up lever guns.
I have an 1895 Marlin CB that was slicked up by Rusty Marlin, the CAS handle for Rob Zimmerman, formally production engineer for Ruger in NH. It's the slickest 45-70 Marlin I've ever handled. I don't think Rob does that work commercially. You can do a word search for him. I think he's now in SC, working for a gun mfg. down there, maybe FN, not sure. He makes custom Mauser actions, IIRC.
DF
Here, set up for CAS shooting with tang sight pictured with a Pedersoli Sharps, both in .45-70.
Edited to add, Rusty is with Beretta.