How to calculate rotation without transform

I have the following operations on my rotations:

 Quaternion rotation = Quaternion.LookRotation(node.position, Vector3.zero);
 transform.rotation = rotation;
 float lookRotation = transform.position.AngleAround(transform.right, node.position);
 transform.Rotate(0, lookRotation, 0, Space.Self);

I would like to get the actual transform.rotation at the end without using gameObject.transform (so without setting the rotation from the LookRotation and doing the Rotate operation) so I can feed that value in to a Quaternion slerp. What would be the best way way to do that?