So, JackBombay, I feel for you, you asked for opinions. Everybody has one. And the feedback is useful. All of it. But it is your bike and your butt that is at risk. Weigh out the advice and do what you think is right.

One line of thinking is that if this does not work out, and let's say the epoxy lets go, then you have the holes in the frame and you still need to get the cable guides on. And you still have the stopping power of your front brake. Your plan B is that you can still braze cable stops right over holes. My local body shop says they can mix a pint of 2K paint if I bring in a part of the bike to color match to. But this is Plan B.

I don't see why Plan A won't work or would be so disastrous.