Are you sure that the plaster will get damaged beyond repair when you try to remove the panelling?
Try removing a little first, in several areas.
Just because plaster is old doesn't mean you have to remove it. It breaks my heart to think that nowawadys people actually think that drywall is superior to plaster. Drywall is (and always has been) a replacement for plaster.
If you think you might have a chance to save your plaster it would be well worth the time and effort.