Spindle orientation might be possible with a 3 phase induction motor. When I get time, that is one of my projects on my lathe. It already has a spindle encoder, is being driven by a sensorless vector VFD, and controlled by a motion controller. The motor is the same but the original drive was a Fanuc, and would it index/orient to 1°, but I think the drive had tighter control than the VFD. We'll see how it goes.
The really easy way to make the spindle do anything you want is to convert to a servo motor. That will index to one encoder pulse. The DMM 1.8 KW servo is a popular spindle conversion. ClearPath has also come out with some larger servos.