It's hard to tell which words came from Wolf and which came from Joseph DiMona, the writer. Can more easily see DiMona adding the "boss of bosses" phrase more than Wolf. I think it's very possible the story happened, just that the date was off by a year or two. For people writing many years after the event it's very common. After all, how many of us can remember what we ate for breakfast yesterday?
I think the story, or a version of it, happened too. There was some kind of reconciliation between the two of them just like it says in the document you posted. But Wolf´s part in this reconciliation (and of course this is just my opinion) may have been embellished and/or enlarged to make the book sell better. If he´s wrong on the year of when he set up the meeting between the two of them, there is a possibility he is wrong on other stuff in the story as well.
I just like to comment shortly on the memory thing. It is easier to remember a big event that happened, let´s say, ten years ago than what you had for dinner a week ago. Because dinners are a daily occurence. It´s a daily, natural routine. Big events like the one in this case, setting up a reconciliation meeting between two of the most powerful mobsters in US history, is not.