Try using this law : North Before, South After.
Means if you are turning to a southerly heading you should stop your turn AFTER south
As you are turning left , the turn direction is from North to South in the anti-clockwise direction. So overturn through south is 160
With a right turn to a southerly direction . Turn direction would be from North to south in the clockwise direction , and then overturn through south would be around 210 °