You actually do not need the angle for that. A rotator should be enough.
You can Find Look At Rotation (current actor position & starting position) and then keep Adding Actor World Rotation until forward vector Rotation from X (closely enough) matches the one spat out by the Find Look node.
But perhaps you do not need to AddActorWorldRotation - not sure how what you’re doing is supposed to work, but it can definitely be achieved with rInterpTo or Lerping rotators - a more subtle approach. But again, you may require specific control over rotation.