He says the production was an initiative of Centauro Film, Madrid, and that J.L. Romero Marchent was involved in the production. He also calls the choice for Malasomma as director rather bizarre, since he had no background in action movies and wasn't really a cult director (like Lizzani or Vancini), but he states that Malasomma was involved in the production from the first minute on.
I don't know, Giusti doesn't say so, but I can imagine that Marchent was supposed to direct the film and that Malasomma (available anyway) took over for some reason.
He doesn't say anything about the end either, mentions only the 15 scaffolds of the title (maybe they invented the title before they had a real script and then had to make up something to explain the scaffolds)
Anyway, Giusti says he didn't like the film then, but thinks much more highly of it now