I prefer him only as a source of info, maybe he might talk with Naruto the same way Kushina and Minato did and the key for this meeting might be the chakra from all bijuu, which is not completed since hachibi haven't given Naruto its chakra yet.
Why I think like that, because SO6P said the bijuus when he created them that someday they will be shown the rightful path by someone. He might arrange it so that when bijuus would find someone they trust(Naruto), they would give him their chakra as a sign of trust, so when all bijuu chakras are collected, he might appear in that person's mind. That is the only way that I can think of for SO6P to enter the story.
The other possibility might involve the other half of Kurama's chakra, or Kurama himself tell Naruto some things about SO6P. But the first theory might be more interesting imo.