As your humble kilt maker my first inclination would be to pleat it to the blue/green/blue stripe arrangement on the red field. This would create a very clean look in the back of the kilt.

The other option would be to pleat it to the other pivot point, the blue line that sits between those two large green blocks. This would darken the back of the kilt and bring out the green more. However, it is a "busier" portion of the tartan. I haven't worked out the math between the sett size and your measurements to see exactly how wide the pleats are going to be at the hip and waist, but depending on how that works out, you might run the risk of having a "dissapearing stripe" as the pleats narrow at the waist (not really the end of the world, but a consideration). In any case the pleats would look "busier" compared with the relatively clean and simple arrangement if we pleat to the other pivot.

I could pin it up both ways and send you photos once I get the cloth in.