"If I were to enlarge it, how would I undertake such a project?"
This is how I do it: I have a set of numbered drills, Harbor Freight, and I use one as a gauge to measure the size of the existing hole, of course with the lock removed. I then decide what the final size I want will be, remove that bit from the index and lay it aside. That leaves me with one or more bits between the 2 empty holes. I take the smallest of those, chuck it in a pin vise and using a thumb and 2 fingers drill the hole out. Repeat the process up to and including the final bit; it's easy, doesn't take long and reduces the chance of breaking a drill.