Spreading an object composed of 2 sprites

i spread a 2d object composed of two textured quads, say head and tale.
if i group them i will get all heads ontop of all tales.
how do i fix this ?
would there be use of a Group (Priority Advanced) where one can sort the order of the slices from all incoming layers? using depth axis without perspective transform makes the sprite disappear rather then fall behind

varying the z-axis should in fact do the job, and the quads shouldn’t disappear if the z coordinate keeps in the range from -1 to 1.

Also, you could increase this range by setting near/far planes using the Ortho node (instead of Perspective).