I'm currently reading POWER UP: How Japanese Video Games Gave the World an Extra Life. In it there's a sidebar where author, Chris Kohler refers to a conversation with video game historian Steven Kent regarding Iwatani and the pizza. (sidebar quote appears on p.22)

I asked video game historian Steven Kent about this via email, and he told me that inhis first interview with Iwatani, he told the story as truth...but that in a later interview, his comments were translated as something like "I wish I could say that this is how it happened." And in Shida and Matsui, volume 1, page 43, he is quited as saying: "it's already passed into legend, so I'm going to stick with this: I took one slice out of a pizza and saw Pac-Man" (my translation).

The Puck-Man story is accurate according to this book as well.

Found this Iwatani photo. Good stuff.

Keep in mind that Pac-Man was the first game to use cinematic scenes after clearing some levels. Good luck on the book, Matt.