Yup - there are 2 "standards". I was wrong on that...
I have 90 degree valve stems like these -
https://www.google.com/#q=90+degree+...tbm=shop&spd=0
Some are the "Euro" size - 8.3mm
I have the other "standard" (Japanese) size - 11.3mm
I would just get the "Euro" ones from a local dealer that sells and services Euro bikes if you can.