I would like to read that script myself. I wonder if any copies exist?
I doubt if the Italians kept anything leftover from a film, but it would be nice to actually see that missing footage.

I read an interview with Claudio Fragrasso about this movie in the book Eaten Alive. It provided some insight into the original ideas for the movie.
He also said he directed all the gore scenes in the movie. He said that Bruno Mattei hated to direct gore scenes.
Lastly, he said the original cut of the film was apparently far more gory and violent than what ended up on screen. He said there was a lot of footage left on the cutting room floor. This might explain why the movie was under running and needed padding with the documentary footage. That a lot of filmed footage was taken out from the final product. While the film does have some violent scenes in it, it is actually a little low on the gore front for an Italian zombie movie.