Very interesting project. On inspection/observation, the steel inserts which substitute for the flints, on the original and Frizzens' pistol as well, appear to be either 'anchored' around the jaw screw or directly by the jaw screw, via a drilled hole, to keep it aligned properly with the nipple.
The only original flintlock lock plate that I have that was used to fabricate a percussion weapon, did keep a portion of the rear of the pan to act as a fence, to at least try to mitigate cap fragments. I'm sure that you'll undertake 'due care,' if/when you decide to shoot it.
Good luck!