Why did they change the story line from the original?
How u got a white dude with a totally different voice supposed to pass as the black dude who white voice is nothing like his
Because it is BASED from a true story. Emphasis on based.
Basically this is a FICTIONAL STORY based from true events. I think a lot of people get that confused. With that all said, and to also address why there was an Italian being part of the Klan, I think it was implied heavily that the Klan were desperate in recruits. I mean they had a FREAKING AD in the newspaper! So many of them were just in denial and accept you as who you claim to be. Which is why they dismissed the difference voices of the same person, or the coincidence of the address is the same as the real Stallworth, or the fact you can LOOK and see that's a Jew based on his features, especially the Jewish nose, all of it is force denial. They were pretty much letting anybody in. They didn't remotely bother to do a background check on Stallworth. Just a phone call and that was that. Only one person was able to see through it, but ironically didn't think about Italian person who told him who is really who.