Interesting info on the hardness testing!
My technique for adjusting headset is (after fully clean and adjust everything, assuming properly milled and faced, stem installed and tightened) set the upper cup to where it's clearly loose and "rattles" when you bounce the front wheel.
Then very slowly tighten the cup until the rattle just disappears, and snug the locknut down.
Now lock the front brake and wiggle the bike back and forth. Do you feel any play? If so tighten just a tiny bit more.
Then clamp the front wheel between my knees and using two wrenches (I use a Campy flat wrench and the Park 7-sided wrench which will not slip) carefully tighten the locknut and upper cup against each other, repeating the test above if necessary.
Final test - to make sure it's not too tight - when you lift the bike and tilt it from side to side, the headset should be loose enough to allow the front wheel to "flop" or fall under its own weight.
I believe that the Stronglight A9 roller bearing headset is a much better headset than a Campy. And I recommend "extreme pressure" grease, not Campy. Use black moly-sulfide.
Mark Petry
Bainbridge Island, WA