Hi Jens,
Do you need front or rear? i used a front DR350 sproket, these are 520 pitch width and have a lip on one side that can be machined or very carefully ground down with an angle grinder to give a set width. The JE sproket No. is 432 and the total width including the sproket part and the lip is 10mm. For a rear i use the 520 SV650 conversion sprokets made by Talon.