Stefan,
Looks OK to me. Don't be fooled by the gap, no washer needed. The centre nut tightens up against the bearing and provides a clamping cylinder for the top yoke. Clamp it wherever it ends up.
The profiled rubber rings need a profiled aluminium ring to go with them, several different thickness rubber rings were used, depending on frame/fork set up. Actually, only the 1000 and 750GTL used these brackets, but the GTL tubes are for 35mm forks so won't fit later triples anyway. When installed, the rubber ring should only slightly be compressed, the tube being clamped between top and bottom yoke.
HTH,
piet