With the geometry of the head in question, I decided to do some investigation into what I was having trouble with. Sometimes in situations like this, I photograph the painting, import it into Photoshop, and then superimpose the original photo. I run the photo through a "find edges" filter and render it in magenta, so I can overlay it and see where things are not checking out.
It's a pretty surreal image in and of itself. It also clearly shows where I've gone astray. The tilt needs to be more acute, the duck-tail smaller, and the nose/lip/lip definition needs to be indicated better.
I'm going to use these studies to inform me as I rework the face tomorrow. I sure learned something, I just hope I can apply it.