hello !

well, I don´tknow if there is any nurbs-head modelling tut out there. But I can give you this link to Julian. He is a wonderful maya artist nad make things - Uaaaah, really great.

But I think his Head modelling tu is for polys.. I´m not sure.
https://www.cg-art.i12.com/mad_1.html

best greetings,
bernhard