Q: Do I need to add the Anti Rotation Notches?

A: No, You do not need the anti rotation notches. A properly torqued GracePESDs will be sufficient to prevent the unit from rotating. The hole can be made with a standard 30.5mm push button punch, like a Greenlee 10807. 

If you prefer to add anti rotation notches, use the diagram below with a Laser cutter or Water jet to cut out the notches.