It would require Jango to really mess up, the coup was a mess, general Olimpio Mourão nearly blew it all when he tried to march into Rio from Minas Gerais in 31 of March, instead of the originally planned 8 of April, LBJ's hesitance to reconize Mazili's government after Tonkin and Castello Branco's plane crash also helped flop the plot.
I do wonder how the CIA would be impacted without the exposing of the collusion exposed by deputy Rubens Paiva's investigations on IBAD and IPES, popular pressure led to american aides like Dan Mitrione, Wernel Walters and ambassador Lincoln Gordon, Gordon was nesrly lynched when mobs attacked the american embassy, only Jango put an end to the biggest riots since Getulio's suicide