Firstly, a health Itachi would be really hard to beat. Also, notice that J-man isn't good with Genjutsu of ANY kind, so I would believe the fight is over before hand.
Anyway, Itachi would just win due to that J-man wouldn't know what to do with the Amaterasu and even if he did TRY manage to not get hit by his Amaterasu, he would have to deal with Susano-o.