I had this issue with my Koga Miyata. I tried to look around for a quick fix but most advise is don't mix and match the parts and it is not worth damaging frame or bearings. In the end I spent the extra on a JIS Dura Ace headset. it's not worth messing about for the sake of a few quid IMO in the end I was glad I did anyway as ended up with a much better functioning and looking part.
I had this issue with my Koga Miyata. I tried to look around for a quick fix but most advise is don't mix and match the parts and it is not worth damaging frame or bearings. In the end I spent the extra on a JIS Dura Ace headset. it's not worth messing about for the sake of a few quid IMO in the end I was glad I did anyway as ended up with a much better functioning and looking part.