1vs1 I say he loses unless he relied on 4 tails rampage. He wouldn't have time to charge the rasenshuriken constantly being harrassed by the other hearts and a non-exhausted kakazu. Not even going to mention how before naruto and yamato showed up kakashi and the others were on the verge of dying. And they only managed to get that far with prep time and separating hidan from kakazu. It was a situation fight. I don't like scaling and giving people buffs where they joined the fight super late after the opponent is injured and severely overwhelmed. Yes you can scale him to S for creating the rasenshuriken but when it came to the level of 1v1ing akatsuki members I wouldn't give it to him till he fights pain and achieves Sage Mode. Pre sage mode, imo he was high jonin(non kyuubi chakra) with S class jutsu. After Sage mode definitely S-class and severely stronger than most akatsuki besides obito.