You can farm this and assassin in ch8. After you are tortured by The Knife and climb out of the incinerator, crouch and takedown the dog followed by the guard beside him. Leave the guard on the left.
Turn right and go up the stairs, then crouch at the top and takedown the guard on the catwalk, open the door and turn left to follow the patrolling guard. I stayed crouched and was able to catch up and take him down as he turned the corner. Turn right, while crouched and take down the guard. Turn back around and go to the room where The Knife is and take him down. Pick up the knives in the sink. Go back to the area with the elevator doors and proceed through the gate, turn left and get into the control room. Throw a knife at the guard.
Backtrace your path fully and pick up all the health along the way in each of the rooms and the closed medic door. Go back down the stairs and go up the ramp past the furnaces. Pick up both health kits which will put you in overcharge. Move through the room on the right and take down the guard up the small set of stairs.
Silent takedowns: dog, guard, catwalk guard, hallway guard, elevator guard (could be done knife throw if you kill The Knife first), The knife - 6 or 5
Knife throw: control room guard - 1 or 2(see alt above)
Overcharged: guard in the room left of start - 1
Restart checkpoint and repeat as necessary.