The map looks great! One correction: in the "prison" section, the north-heading hallway starts 10' after the staircase. Also, before each 10' cell, there is a 10' niche. Neither detail is super-important, but if you want accuracy, there ya go.
The door into the new room is in the center of the north wall. The south exit hallway is in the exact center of the south wall. The eastern door is at the 50' mark.
And yeah, this one is much more "sprawl-y" than either Stonehell or Sakkara.