Rob,
Most Darnes actually have a rod through the wrist, that has wood screw threads on the outside, and machine screw threads on the inside. The bolt goes into the rod from below the action, after the rod has been smeared with pig fat, and tightened, quite tight.
The Bruchet's design is a bit simpler with a 10mm bolt going in from under the butt plate.
I've seen a successful bend on a Darne, actually it was more of a twist than a bend, but, I don't recommend it. Getting the fit right on a used Darne is pretty much limited to LOP adjustments.
And, luck.
Best,
Ted
