Do stator windings on a permanent-magnet synchronous three-phase ac motor have sinusoidal distributions?
Yes:

A PMAC motor has an (approximately) sinusoidally distributed stator winding to produce sinusoidal back EMF waveforms. (Similarly a 3-phase AC induction motor does as well).

A "brushless DC" motor intended for six-step commutation may have trapazoidally distributed windings.

A good summary is Here

An interesting graphical representation with animation is Here