Senior Retro Guru
Bingo! what Boy Burning said. It does fit after all, after some deep cleaning of the threads and some de-burring on the back where the keyed washer groove was (that beginning part was causing the trouble) the headset does thread on fine. I was indeed comparing it to some cheapo Shimano and Ritchey stuff that was all loose and floppy, but I wanted to make sure the threads are compatible before I try to force it through.