BSM Naruto vs Sasuke (theoretically even with the curse mark given to him again) would still be a shit show.
Simply because... chakra. How can it be a debate? Naruto naturally has maybe the same if not 1.5x more chakra than him then Kurama has at least 25x more chakra than Sasuke. If it came down to raw power and the way they fight it'll be completely even, but Kurama is the X factor, Sasuke's EMS keeps him further in the game, but to no avail, Sasuke would lose low mid difficulty.
Rikudo power ups is what made Sasuke equal
Simply because... chakra. How can it be a debate? Naruto naturally has maybe the same if not 1.5x more chakra than him then Kurama has at least 25x more chakra than Sasuke. If it came down to raw power and the way they fight it'll be completely even, but Kurama is the X factor, Sasuke's EMS keeps him further in the game, but to no avail, Sasuke would lose low mid difficulty.
Rikudo power ups is what made Sasuke equal