Originally Posted by
John E
You may want to consider using two adjustable cups instead of one fixed and one adjustable, so that you can fine-tune your chainline.
This trick might just make it possible to use a Series 3 spindle with original thin adjustable cups. Since the Series 3 spindles are a couple mm narrower between the bearing races, you'd need to be able to take up this slack with the adjustable cups.
Gotta remember to give it a try sometime.