No idea about the copyrights
The name Sergio Corbucci as producer is clearly wrong. Atillio Riccio is not mentioned on the credits (they come up with another name), but he's mentioned by Marco Giusti in his standard work Il Dizionario del western all'Italiana. That's where Alex Cox no doubt found the name.
Riccio apparently was some kind of executive producer for Adelphia CC (the company is mentioned on the credits)
Thanks for the correction, I'll change the info later (I'll check a few other sources first to be absolutely sure)