Rather then rechamber ( or possible barrel set-back and rechamber ), IF you are determined to keep it, and use it with more readilly available ammo, why don't you consider a re-barrel job, with a factory contour barrel, so your stock will not need modifying, and rifle could easily be returned to "as produced" ( have a small "witness mark" scribed where it won't be seen ). You could go with .223 or .204, ( the.204 is a necked-down .222 mag ).
Like Graybeard mentined, you have a real classic, as I'm sure you know.
Mark