Edit: VO's website states that ISO has a pressed race of 30.2 and a crown of 26.4; JIS uses a pressed race of 30.0 and a crown of 27: http://support.velo-orange.com/#headsetarticle.html So I guess I have a weird headtube dimensions and need to mill it to 30.2 or that my I'm doing a spectacularly poor job of measuring the tange levin headset I pulled off my bike.

In replacing a headset what are the key dimensions? I've always thought that the important dimensions are the crown race, the pressed race dimension, threading, and stack height. Is there something I'm missing here?