Can you share with us what epoxy was used in this magical process?
West System's G-Flex. It is microscopically flexible, which is important when the parts being connected will expand and contract from cyclical heating & cooling + cyclical humidity changes. The enormous tensile strength of the diamond-hard varieties (like T-88) actually works against a long-term bond in those situations, because the glue never moving would cause the wood fibers it's attached to to slowly shear over time.
And was the draft hole breached at any point? looks like it may have gotten awful close
Nope. Bit of luck, there. If it had intersected the airway, the right fix would have required over-boring it slightly and then sleeving with stainless steel tubing to prevent the tars & etc created by smoking from attacking/softening the wood around the epoxy. That wouldn't have been a problem in itself---an ss-sleeved airway smokes no differently than a wooden one, and is easier to keep clean in the bargain---but it would have been visible when the stem was removed as a silver ring in the bottom of the mortise. As it is, the repair is undetectable. (Even knowing it was there I couldn't find it using magnification after refinishing. Not sure if a black light would show something... I didn't think to use one before shipping the pipe back to its owner.)
