Carl Paoli from gymnasticswod.com discusses head positions for handstands.
Again, it boils down to the question of “What’s the purpose?”
He emphasizes the importance of having a visual cue while being inverted.
Looking at a point in infinity makes things unnecessary harder. But that doesn’t mean you should break your body line and completely stick you head out either.
Ears should be touching the shoulders, look at ground -> get better visual cue with little extension in the back.