So, in this battle, as it says in the title, Naruto is the current Hokage. He is not allowed to use neither Kurama, nor SPSM. So the only amp he can use is SM.
Itachi is the one from part 2. He can use his abilities to the same degree he did when he was an EDO tensei. So he won't get tired after one amaterasu or after 10 seconds of susanoo usage. To be clear, he is NOT and EDO, so he doesn't have the edo regeneration. He has kind of an EMS if you will, but he isn't able to conjure a Susanoo with legs or anything like that. Only feats that he displayed.
They know about each other from their previous encounters from part 1/part 2/ the war.
They fight in an opened field.