for a new or new-to-me lock, and you have no flints at all, to make a wooden flint that fits well, then use those dimensions as need be. doesn't need to be exact and if a tad wider flint is used that's no big deal. flint length is more important and that will be reflected in the lock's geometry. at half cock and with the hammer steel down over the pan you'd want that jawed flint to be up high on the frizzen face and nearly touching it.