Hi This would be a second vertion of a fourm wrinin by some one else on modling a head. From what i heard and seen highlighting locators and telling them to creat a mesh is not allways the best idea so foe a head or face what would you do would you use the sphear object and then just move points so they match you locators.

I think that you cannot do it using a sphere and snapping it to the locators.
The best is to create the mesh face by face. It's long and fastidious but you will have a final result nearer from reality than with a sphere promitive.