On some Panteras, the plastic cover bulges out toward the pedals. Its possible to punch a hole in the right place in the cover and add a long self-threading screw, and carefully tighten it to pull the cover towards the center to the car.
But first you need to determine what's solid back in that bundle of wires et al, before drilling. And you ARE dealing with a 55 year old sheet of plastic of unknown brittle-ness....