As said, the timeline is tight. And everything I've read says Gigante went to Amuso and Casso and told them to plan the hit. The implication is they were running things at the time, some sources say Corallo had already chosen Amuso as his sucessor before he was convicted because of his closeness to Christie Tick. I dont know how that coincides with the Buddy Luongo hit, as D'Arco claims thats who Corallo really wanted to be his successor but Amuso and Casso had him killed.