If you are talking about 1-7/8 hole you just have to find locks that will go through hole and install as usual. If you can't find smaller than 2" you'll have to grind hole bigger. Any hardwear store sell's 1-1/2" drum files that fit in electric drill. It's time consuming to grind out holes.

Or take the door off and re-drill the hole using a drill press and forstner bit. A door drilling jig with a hole saw would also work if the jig provides enough support to the hole saw to allow you to drill without a center bit-- you could easily make such a thing.

My worst shop accident involved using a spindle sander on the inside of a hole where the drum was close in diameter to the hole, so I shy away from that approach.