Hi Hanno & Alex
Good question and point about repacking the front steer drive ball and hub. When I'm working with a clean one for a complete repack I go with the amount listed in the manual or drivers hand book which for C60S - C60L as being 4.5 lbs of wheel bearing grease (listed in capacities section) while in the Handbook it says 2.5 lbs each. So much for clarity.
Now as to over greasing my long term driving experience with my HUP is that the outer grease seal is stronger than the axle side so that if too much grease is pushed in over time it goes in the axle tube and just sits there.
I add 5-10 squirts of wheel bearing grease into the center of the ball each spring. See
http://canadianmilitarypattern.com/Tools.html about half way down the page for how. This can be done through the plug hole on the ball. I like this method of put a little new grease in each year because it gets the new grease into the center of the steering balls.
Cheers Phil