Dan,
Some early Ketlands were beveled along the face, like Mike's great photos show. But not all were. So if you are building a copy of an antique, but sure to study that detail well if it matters to you.
For example, here is a detail of RCA 124. It is only beveled on the top edge just behind the cock. Most of it is not beveled.
Hope this helps.
Whet
PS: If you want to see a clear, detailed photo of this lock, it is in Shumway's Longrifle Articles, Vol II, p 190, and again on p 216. (also in Muzzle Blasts, Jan 1970, and Sept 1981, as Shumway notes).