Wayne, do you recall where you saw the upper clamp possibly being raised ? I surfed sohc4.net and found some information, but nothing specidic to that.
What i found on soh4 was the All Balls 22-1011 kit comes with two different thickness spacers; one of the spacers to be fitted on the bottom of stem. Did not find any info specific to fitting kit to 69/70 models, but did find info on fitting spacer to the K1. Even in the couple K1 specific posts i found, there was conflicting info if the thin or the thick spacer was to be used, but seems the concensus was to fit the thick spacer. (Would think K1 bearing setup, distances, etc, same as 69/70.......)
Re: 2157 being a rider, i'm not too concerned about original appearance, in the event the upper clamp would be raised, but if it is too high and appearance was too greatly affected, i probably wouldn't want that and would go with original ball bearing setup.
Given 2157 is a rider, the idea of tapered bearings giving more positive steering and improved handling is certainly attractive. Hence my interest in the tapered bearing setup.