Another vote for Numrich, they usually have hard to find stuff. Thinking back I ordered some parts for a replica 1887 a few years back and got them from www.jackfirstgun.com, they don't have an online store, you'll have to call them, but they're great with customers. I'm pretty sure they had original parts as well, good luck!
P.S. Welcome to TFL, hope it helps you as much as it has me