You may well be able to polish the sear, or refile it to the proper angle.
But, until you have the bridle resolved, I wouldn't mess with it.
The owner of TOTW recommended a metal worker in New Hampshire to me that would be a very good shot to help you with this. I think his first name was Ed, and I don't have his name any more. Calling TOTW would be worth a shot. (Especially if Beauchamp doesn't have the part.)
Could also look for a beater Pietta with a decent lock. Stranger things have happened.