I am not familiar with that gun, but here is some suggestions that might help
Dixie Gun Works has a full time gunsmith, if they don't have it, they should know where to find it. 731 885 0700
VTI Gun Parts sells about anything you can think of concerning reproduction guns. They may have something that will work. 860 435 8068
If all else fails go to www.oldwestgunsmith.com
The owner is one of the better known gunsmiths and authors in the country concerning antique weapons.