Naruto and Sasuke could win in a scenario where PS was boosted by a chakra cloak and Senjutsu, i personally don't see the gap between his PS and Madara's to be that much larger than the one between a V3 and PS (how big is Yin-Yang Chakra Cloakìs boost? x12? Maybe even more?), so in my opinion it would be near that level, considerably weaker offensively though considering he never showed a second blade like Madara's, and defensively since Madara's would be bigger thus thicker. I'm confident that BSM Naruto's firepower is much superior to his BM version aka Half Kurama, and slightly less than half of the Bijuu's firepower is composed of his own.
Maybe they can win this extreme diff if conditions were the ones above, your scenario (BM Naruto)? They lose for sure, only a matter of time.
Madara wins, doubt that a combined Flash BD is causing anything more than low-moderate damage to PS when 12 big BDs
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and Chojo Kebutsu was required to plow through it, Madara's Kurama alone can replicate that firepower, let alone PS along it.