correct 'roll' in panoramic material?

For a VR project I captured a few panoramic photo’s of an existing office. I project these photos onto spheres in the project. Once you trigger an icon, the 3d model is hidden - the sphere is visible. In the sphere you can look around (looking at the projected photo) - and by using the controller you can switch back to the 3d model. The pov is the same so you can easily see the differences between the existing office and the 3d model of the remodeled office.

It all works fine but - last time I took some panoramic photo’s the tripod wasn’t 100% level. With my material setup (see pic) I can easily correct the ‘yaw’ of the material. Is there a way to correct the ‘roll’ in this material?

Suggestions are very welcome!