No, if your equation 0.5 nature energy = 8.5 raw chakra is true, that would mean that nature energy is 17 times stronger than raw chakra, not 8.5.
But that equation isn't true, we don't know how much chakra Sasuke took from the bijuus, and we don't know how much chakra Naruto used to mix with natural energy.
But that equation isn't true, we don't know how much chakra Sasuke took from the bijuus, and we don't know how much chakra Naruto used to mix with natural energy.