I don't know how bad double black is for your deck, but I see Cuombajj Witches frequently in Pauper lists (if not the mainboard, in sideboards) to kill X/1s, and is also another way to attrition opponents.

Have you ever thought of Portent and Gitaxian Probe?

portent is little worse than ponder, and it is not a card draw spell. Gitaxian probe - it is mostly for combo decks or aggro, not for control.

+1 for the deck, cause I LOVE EVERY Draw-Go control in pauper!

But about deck - in 60card one, for me there is no room for more than 2 teachings (even 2 is to much. For example Think Twice is much better early, when D-Gc have hard time to stay alive, but you can not do any sheningans in late game, like tutor for Whispers of the Muse or tutor for Perplex and then tutor for talisman or Bloody tome). In the other hand - Think Twice is just batter than Accumulated Knowledge, but this is just my own conclusion after lot of games.

I recommend 4x chainers, 3x exclude, 2-4 prohibit - for sure. And to not play sprout swarm if you have a lot of other creatures.