Did this one work?
With the length of the stocks varying several inches in length from one order to the next, I planned to zero from the right back region which is where the metal fits in the grip and is the constant. The top portion of the arc on the top right portion is about .4" behind the metal.
The bolt holes on the left side are 3.1" apart-but this varies with different recoil pads.
I have fixtures holding the wood up off the table since the wood thickness varies.
With the variations in length as well as thickness of grip region in most orders, I see the machine doing the rough shaping and the final shaping will allow for the variations.

Tony