Try something like: always set angle to anglediff*0.9
The bigger the angle difference, the faster it will turn (there are various ways to cap the speed), and it won't overshoot when it gets to the right angle.
Also, what I typed won't work exactly because it doesn't have timedelta. It should look like: always set angle to anglediff*(somenumber*timedelta) but I can't remember what somenumber's supposed to be for that. Try experimenting with what number should be there.