Ignoring the kyuubi's stregnth, He will probably become stronger being now able to use more chakra given what you are assuming is correct.Yeah dude, i think that's possible. Since rasengan requires so much focus of chakra, the seal is preventing him from having a full control over his chakra. I was also wondering, if naruto controls/becomes friends with the kyubi does it mean that he won't have the seal on him and have all of his original chakra that was used to block the fox?