From what I hear you saying, it is entirely possible that if I were to use the white belt marks I will find that the notches in the HM may in fact be at the 6 o'clock poistion when things are lined up. Not?

Forget the white belt marks. People read too much into them. They are only for the initial positioning of the belt. After just one revolution they won't line up again till the next full moon.

As long as the 3 sprockets are in the correct relationship (and not moved when the belt is installed) and still in the correct relationship after a revolution or two, that's it. End of story. Some new belts don't even have those lines.

When guards and HB are installed, their offset references are valid. They are offset to get them out from under the fan pulley, so they can be seen better.

Can't say where your HB notch will be, based on all you've said. But around 12 o'clock is about where it should be -- to be matched with with degree marks on lower belt cover.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.