What are you trying to do? Reface the bottom or mill the size smaller? Or both?
Hand files can be used if the size needs to be reduced. I had a Japanese fork with 27mm JIS crown race seat but needed to use an ISO 26.4mm crown race. A coarse file was gently used, checking often with calipers until it was close. I switched to a fine file until the crown race popped on. It's not that big of a deal.
You could call around to shops and see of someone still has one. This work isn't done frequently however but you might be in luck if you found an older mechanic who built frames or custom frame shop. A frame builder here in Atlanta offered to do it for $20 but it was a 1.5 hour drive so I just did it myself.
-Tim-