There some other choices, Chris. First, if you cyl. has fairly recently strated leaking (i.e., isn't too rusty) you may be able to successfully rebuild with an appropriate kit. Some people can do this well while others can't. If you're in the latter cateogry (I am) than I'd suggest that you take the cyl. w/ kit to a "brake and clutch" firm which specializes in rebuilding brakes and clutches.
Over here, they mostly do work on heavy equipment, big trucks, etc. but for them, if the cyl. isn't rusty, rebuilding is easy. My local company quoted a $15US labor charge if I supplied the kit and a good cyl.
Your second choice is to find a company that resleeves brake components for collectors cars. If the casing isn't cracked, they can repair your oem master cyl. to new condition.