I don't think so. Conversions came into fashion (due to technology advances) after the CW.

If you must have a revolving cylinder rifle in your story, you may want to consider having your character use a pinfire cartridge revolving rifle. There is documentation of the use of these in the CW. While there were some made by independent Belgian and French manufacturers, most were LeFaucheaux brand since Lefaucheaux held the pinfire patent.