Meanwhile, back at the OP ranch...
If you are replacing a mountain or road fork that had a 26.4 crown race diameter and your replacement fork has a JIS 27.0 diameter use a sharpie when filing it down. Repeatedly filing off one layer of Sharpie at a time will help you remove a fairly consistent amount of material all the way around.
(I learned this from a post on the MTBR vintage forum quite a few years ago).
If you are replacing a mountain or road fork that had a 26.4 crown race diameter and your replacement fork has a JIS 27.0 diameter use a sharpie when filing it down. Repeatedly filing off one layer of Sharpie at a time will help you remove a fairly consistent amount of material all the way around.
(I learned this from a post on the MTBR vintage forum quite a few years ago).