...No. Neji isn't using Full Body Blow when he's writhing on the ground in pain, for one. Secondly, Full Body Blow would merely push the flames away, at which time Sasuke uses Enton to guide them back. Neji's movements are predicted with Sharingan and he's honestly ended with either Chidori Spear or Base Chidori.
Writhing on the ground in pain? Are you one of those people who still thinks Amaterasu is as hot as the sun?
Karin got hit with Amatersu: Did not wither in pain
Samurai got hit: Amaterasu did not even burn them, it didn't even burn the armor they were wearing. Please
Full Body Blow can remove the flames from his body. Guides them back to him? Full body blow again? Nejis movements will be predicted his movement speed is equal to Sasukes. What about attack speed though? Nejis attack speed is superior to Sasukes. He will be taken down by 64 Palms.
How many Amaterasu and Blaze release you will say Sasuke can use until he burns out of chakra?