When we took two different cars apart (71 and 74) and the cupped side/relived side was toward the outside of the car. We assembled it the same way and have had no problems. I think it was designed that way to give a little extra clearance with the splines on the axle and yoke. You will notice that as you slide the yoke on the axel the splines are pretty close to the top of the yoke spines. If the spacer between the bearings has much wear the yoke can stop on the axel splines before the spacer is held tightly between the bearings. This also moves the full force of the compression away from the splined area on the yoke.
Not sure how well I explained this but hope you can follow the attempt.
Mike
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