Great writeup! One thing to watch for is keeping the drill parallel/flat to the axis of the case. I had a Silix case a couple years ago that the axis of the tube was angled down when viewed from the lug ends... so the stem was always stressed and bending as it turned. It was tough, but it was redrilled flat so the stem went straight in to the movement. Another thing... Silix used to make a divot in the case where the tube seats. That resulted in the crown screwing in too far when the tube was fully seated. You can correct that by filling the divot with JB Weld, grinding and polishing flat, then drilling and tapping.