Hutch,
Sounds like you are halfway there if you have workable brass on hand & a chamber cast, I see CH4D lists dies (call Dave for availability) Thought I saw Mike mention he had some originals if trying to establish factory dimensions, if not he has instructed you in how to cobble up a couple for fireforming which will result in formed brass to fit your chambers. I have a couple pieces of original brass in my collection & if I can be of any help let me know or PM your ph# if you would like to chat & I will give you a call.

m-4