I've tried a few head packs but none of them remain 100% vanilla accurate (ren hair, models that don't resemble their vanilla counterpart, etc).
So far, the only 2 that come close are Better Heads 1.1 and Vvardenfell Visages Vol I but even those contain a few inconsistencies (as mentioned above).
Vvardenfell Visages has these weird Jessica Alba & Salma Hayek imperials. I'm glad Westly's working on them. Celebrity heads simply don't appeal to me.
Westley's Head Pack seems that it would be perfect and exactly what I want... too bad it might take a while before it is truly complete. I understand it's been WIP for many years.