66 Barracuda headliner install problem

I'll assume you have 2 small tension wires on the rear most bow. This head liner must be installed from back to front.
I had a similar problem but... mine was a 67 notch back. The box ( PUI brand ) was marked correctly 67 notch back but the dang thing didn't fit. Waaaay wrong at the same place as yours. Bows 5,4,3 landed correctly. 2 and 1 just wrong. I decided it must have been 67 fast back piece in the wrong box. I called PUI, they said replacement in 2 weeks. I was in a push to get glasses reinstalled so I called Legendary, they said approx' 2 weeks. I called Year One, had another head liner here in 2 days. It fit absolutely perfect.
PUI did send me another about 2 weeks later. I resold it without ever opening that box.
So now I'm wondering could a simple screw up in panel/section order at the sewing machine be the cause? who knows? I can only suggest you call Legendary . Good luck.