Sorry you are experiencing difficulties, usually it's not so difficult: the differences in the pressed-in CUP and RACE dimensions between the JIS headset parts and ISO parts are usually so small that there is no problem. As you see in the Park chart, there is a tolerance range for JIS and ISO, so you can get anything from the best case (29.9mm vs 30.0mm) to the worst case (29.8mm vs 30.1). That's big enough (.3mm) to scotch the fit. Your best bet is to buy the new HS that fits tight all 3 places where it's pressed. But for you who are strapped or stubborn, the word is "knurling"...it can raise the metal enough to improve a loose fit. Mechanics have used it many a time, but usually never tell. You can do a "dirty" job with a sharp pin-punch, just make sure to support the part(s) to prevent deforming it...works on the crown race shoulder, too. BTW, check the inside of the headtube to make sure it isn't slightly deformed or over-agressively prepped, that can make a sloppy fit, too.