The sad part is that to achieve a good head articulation, I had to cut a piece to have a 3,5 L axle (it was a bootleg axle). This way they end up being slightly higher than the original build.
Using a 3L axle will leave the head in the same position than the original build, but really limit the head movement to the sides because the head collides with the torso (they need to look up to look to the sides). On the other hand 4L axle give them a neck too long.
I’m mad at Lego. They could easily have give us head articulation for Metrutoran if only the torso piece had this design (and no need of half stud connection).