Replacement,
That's the beauty of Doctor Travallion's butt graft. All the hard work is in the inletting. Glueing a chunk of wood on the back end while retaining the inletting saves a tremendous amount of high skill work and the "fun stuff" of shaping the butt to dims desired and refinishing. Some checkering recutting is also needed. But all said and done, it's much less work than inletting even a machined blank. A good option for the inletting challenged like me.