Hi!
Problem with using a drill bit to enlarge a hole in wood (or any material) is that it can wander sideways a bit!
Best way to enlarge a hole in a prop is to use a stage reamer!

And balancing is soo easy to fix with just a file and sandpapper! Adding anything to
(spinning) prop scares me. We are dealing with props spinning at high rpm here, not full size props at low 2000-3000rpm!