Grandpa's is highly recommended. You will probably never need the cutoff function. Applying a little medium strength Loctite could hold the remnant in place and not interfere with the function of no drill sights. Just be sure it is aligned correctly before applying. Blue 242 Loctite will wick in a fair depth if applied to the boundaries after correctly locating the remnant. Once it hardens it will be difficult to remove. The original cut off even though the cut off function is not needed will be easy to remove for thorough cleaning. Kind of depends what your goals are to which way is better.

I do not think we have seen photos of your Krag, seeing what you have and understanding your goals may get you some better answers.