As I've said earlier in the thread, 6 classes isn't meant to be any kind of ideal number, it's a strange place in between the 3 classes of od&d and the 12 classes of 5e. That's what makes it a "challenge."Only need 4: Magic-User, Fighter-Pwrson, Rogue, and Cleric. Everything else is a Subclass. Done.
So how would you get from the core 4 classes to 6 classes that are interesting and/or make sense to you?