I you bend the cock too far, just heat it up and bend it back to where it was.
I bent the cock on my bess and had to use flints bevel down, for the most part. Long flints work ok bevel up, but need to be turned over as they wear.
I also bent the frizzen to the rear of the plate, and gave it more radius.
With those modifications and after pack hardening, it is a reliable sparker.
I really like Hammer's idea of clamping bar stock in the jaws and rotating the base of the cock in the vise to achieve a more precise amount of bend.
God Bless,
J.D.