Good demo of the Ninja choke by the guys at Invisible Jiu-jitsu. This choke is a sneaky technique that you can use against any level opponent. The element of surprise will play an important factor in pulling this one off.
Using the far side of your gi will be more effective, but you may also pull it off with the near side lapel. However, you would have to consider readjusting the position of your hands to eliminate any space.
Before moving to north-south position, it is critical to establish the placement of your lapel on your partner’s neck. And, don’t forget to block his hip otherwise the choke won’t work.
The video dives into a bit more details. Enjoy it.