The hard part would be getting to that from this point, because green balls fired by the bishop do not gain the damage multiplier bonus for some reason, so I'd be downgrading while working up to that. Green balls are like plain balls if you don't have any actual attack panels.
I was thinking about just going all-in on healing only (with no other panel types) paired with the bishop to see how it goes, making every panel eligible for a crit. It might work because with all panels healing, you'd likely gain ~40 max HP and heal ~336 HP per spin (before any multipliers from the balls).