I checked inside and outside of all bearings and races with a caliper. The lower OE NSR bearing and races on the left is 1.5mm shorter then the CBR bearing and races on the right. The upper bearings and races are the same thickness on both motorcycles. The inside of the bearings and the outside of the races are the same on both motorcycles.
The 1.5mm makes no difference as there are plenty of threads on the stem.