Just take a look at Madara's unstabilised EMS Susanoo, and Sasuke's current EMS Susanoo.
Madara's EMS Final Susanoo (Unstabilized version)
Sasuke's EMS Final Susanoo (Unstabilized version)
If you look at the two closely, you can see that they have the exact same characteristics (the flickering chakra, the arms, the eyes, and the jewels on their foreheads) this indicates that they are somewhat similar in a way. Now what did Madara do to his Perfect Susanoo unstabilized? He stabilized its chakra and it transformed into this.
Sasuke could possibly do the same to his Susanoo by stabilizing its chakra, then once his Susanoo reaches its perfect form, he should gain the Yata Mirror and the Totsuka Blade.
And by using those tools in combination with his Amaterasu Sword, he will be able to fight on equal terms with Bijuu Naruto because since the Yata Mirror can deflect any attack, it should be more than capable of deflecting Naruto's Bijuu Bomb and the Amatersau Sword will be of a major problem for Bijuu Naruto to deal with since the black flames can burn anything. I'm not sure about the Totsuka Blade sealing Bijuu Naruto away, but it could still be used as an additional weapon.
Here's proof from the Third Databook and chapter 390:
Also for those who say that Madara needed the Rinnegan to stabilize his Susanoo look at what he says here:
This proves that Perfect Susanoo is strictly an EMS technique and it also proves that he has used it in the past, since he awakened the Rinnegan when he was near the end of his life.