Regardless, I still believe Naruto had full powered kurama and no one can PROVE he didn't. I can basically prove he Did because manga facts say bijus regenerate.
I also believe that number of tails don't equal power as shukaku and gyuki said they don't. Or even if it does, that doesn't mean the other biju cant win with their unique abilities.
From what we see Kurama body and soul was split in two, what proof do I have, here is the proof.
When Minato sealed half Kurama, Yang Kurama shrunk because of decrease in chakra. Naruto got Yang Kurama.
When Minato was in the war we see Minato has Yin Kurama with his unique soul. Minato and Naruto Kurama have different souls and personality. So there the proof that Kurama body and soul was split up.
As for Ginkaku and kinkaku we are never shown they have Kurama soul at all, just Kurama chakra.
Now that we got Kurama soul and body out of the way, its time to talk about regeneration.
It is that Bijuu who uses up too much chakra or lose lot of chakra can simply regenerate, but Dead Reaper Seal is different, when a part is sealed, it can't be regained unless someone unseals the Dead reaper seal and merged with the sealed part.
Orochimaru arms got sealed and it never regenerated even when Orochimaru stole someone body.
Conclusion
Yang Kurama < 100% Kurama, which means Yang Kurama is only 50% of full Kurama
Yin Kurama < 100% Kurama, which means Yin Kurama is only 50% of full Kurama
It was stated when Minato and Naruto Kurama joined together by fist bump that Kurama chakra got stronger.