John, I couldn't agree with you more about any attempt to adjust headset bearings with attached wheel, bars and cables is starting with a big handicap. However, some say that stem should be installed during this procedure because when its tightened, the steerer tube is shortened (deformed?) to an extent that adjustment is affected. Since I do not install stem, I'll leave to others to verify this phenomenum, but I will keep this in mind and check for it during my next HS service.
Please excuse me for so many recent postings on this and closely-related subjects. Some have suggested bordering on Off-Topic but I found this discussion facinating, very informative and potentially life-saving to increasingly expensive and hard-to-find vintage parts.
Jack Romans
Sacramento, California