I don't believe Vito was in any position to anoint anyone as boss by the time he died in prison in 1969, most of the family had long since stopped paying him anything but lip service by then.

And Tommy Ryan as boss would seem to be contradicted my those Mary Ferrell documents where Ryan is talking about lining up support behind Benny Squint as boss with himself as Lombardo's underboss as early as 1965.

But I never really bought the story of Gambino ordering the Ryan hit, because it seems unlikely that the Genovese's would just stand by while their boss get's whacked by another Family. Also because it seems the hit was carried out by Chin's crew.

My guess is that Eboli did borrow big money from other mobsters, including Gambino, Tramunti, Evola and maybe Benny and Funzi among others, to fund a major drugs deal and couldn't pay it back when it went wrong. There are stories of Ryan getting hooked on pills and booze too and repeatedly shooting his mouth off. The scenario here is that Benny decided that his underboss, Ryan, was becoming a liability and had to go for the sake of the Family. Similar to the Willie Moore mercy killing in '53.