You do not notch the barrel with a drill bit guided by the compensator. It will try to push to the outside of the curve, and wallow out the holes in the compensator. Take it to a gunsmith who has a machine shop setup. That is a job for a mill to make that cut.
Sorry about your Thompson- squibs suck. And no to locktite. Do you know the one thing that makes locktite release? Heat.
What we have here is... failure- to communicate.