I think this deck would be better without the pure mill sorceries. I have a similar deck and I've found that often you can't afford to 'do nothing' on a turn. Well, of course, it's not really doing nothing, because some cards are affected by them, but in the end it feels like doing 'not enough'. Especially the Tome Scours seem weak.
I would advise to replace those with even more removal. Devour Flesh and Ultimate Price come to mind. It's a big plus that those cards are instants, because this deck really wants to handle things instant speed. Yes, those cards don't mill the opponent, but I've found that this deck wins most games with a huge Wight of Precinct Six or Consuming Aberration anyway. And if the opponent handles these threats you just prolong the game until they are milled.