Converting 3D Rotation to 2D Rotation

 private void PlayerRotation( float RotateFactor_Y, float RotateFactor_X, float RotateStrength )
 {
     Vector3 TargetDirection = new Vector3 ( RotateFactor_Y, 0f, RotateFactor_X );
     Quaternion TargetRotation = Quaternion.LookRotation ( TargetDirection, Vector3.up );
     Quaternion NewRotation = Quaternion.Lerp ( PlayerTransform.rotation, TargetRotation, ( RotateSpeed / 100f * RotateStrength ) * Time.deltaTime );        
     PlayerTransform.rotation = NewRotation;        
 }

Converting a 3D Joystick Script to work with a Top-Down 2D game to rotate on Z-Axis instead of Y-Axis.

Moving things around with no success, any suggestions?

I know it involves these 2 lines (+Vector2, not 3)

     Vector3 TargetDirection = new Vector3 ( RotateFactor_Y, 0f, RotateFactor_X );
     Quaternion TargetRotation = Quaternion.LookRotation ( TargetDirection, Vector3.up );