The head on quads points not quite down and not quite forward early on but an angle.
It could swivel over a few millennia as the spine becomes more vertical, moving the 1st joint under the cranium for better support.
Regards the spine, I would love to see the spine of pre neandethal.
As is, the Pre neanderthal, going back enough, would be the quadruped, with the straight spine, therefore, the rotation to a more vertical stance could have occurred earlier than the reshaping of the spine, the reshaping would be easier to withstand compression vertical forces, as it would bend more, and take the vertical load, rather than be too rigid and blow a few inter vertebral disc nuclei, making it easier for the predator to catch and eat them. (dead end, if you will!)
Thus, it is possible the curved spine was in fact a result of vertical stance, and not necessarily during the transition.
Thanks! I expect we will see that spine, perhaps even during this, our current lifetimes.