8 till 10, if you only count Mushashi and Yamato.
But they are not as capable as Yamato and Mushashi if you got 8 or 10. They cant take 50 dive boms and about 10 torpedoes like yamato class did easely.
These are battlecruisers with a nice speed, and less armor.
If they'd beefed up the armor, perhaps they'd have made nice treaty battleships. Then again, we all
know how the Japanese regarded treaties back in the early days of the Shōwa period...