I am far from a lock expert, so take this with a pound of salt please.
I’d love to try doing that. Two things that stick out at me from your pictures:
Looks like that cock would not work well on that plate, referencing the position of the frizzen. Cock screw hole seems to be lined up in the picture, so if you imagine the arc of the flint in the cock, it will strike in the lower half of the frizzen. I think you want it to strike much higher.
Next is cosmetic:
If you convert it to flint, get rid of that 90degree angle down from in front of the frizzen screw to the nose of the lock plate, does that make sense? Those two sharp corners from the top of the bolster down to the nose of the lock plate reek of percussion lock.
(Edit for clarity) I mean round off those 90 degree angles.
Hope that all makes sense.
Cheers,
Norm.