3/4" to 2 1/2" hone at Princess Auto for 8$.
KD and Lisle make them and should be in pretty much any parts store. Worth spending the money if you want rebuild any brake cylinders. You will end up with a proper finish for the seals.

Alllll good advice! I had an idea the emery-paper might work.

I've had the fire going in the garage for a couple of hours, and will be out there soon.

J