Keep your eye on eBay, the prices have really climbed for these hammers.
You would need the 3rd Type or "C" style hammer.
Dixie Gun Works carries these in the rough very cheap but you have to drill and file the square hole for the tumbler. Not easy as it has to be the right angle for it to work properly.
I can help you with the firing pin. Email me at firstname.lastname@example.org.