I am about to embark on the same task for my Grand Son - Stan where did you get a hard thin red rubber pad ? I believe that one off of a old Ruger Rifle would be ideal, but I haven't located it yet.

To prevent the wood from splintering, how about making a very light 1/8" cut all of the way around the stock first ?

Mine's a tale that can't be told, my freedom I hold dear.