With my SMR I relocated the buttplate forward and down a touch. Of course reshaping the buttstock was required afterwards. It's not all that hard, since there isn't any opening for a patchbox cut in!
Jim, a possibly simpler solution to accomodate other LOP for the Colonial might be to not cut in the patchbox recess, and leave extra wood behind the cheekpiece and farther back on the buttstock. Leave inletting the buttplate and the patchbox, to the person purchasing the kit. It is easier to alter the geometry a bit if there is extra wood front/back of the cheekpiece, and in the rear. Depending on how your CNC code is set up, that MIGHT not be too difficult a change. Of course it requires more tools and skill on the part of the builder.
Gerald