Correct Fitting 68-72 Chevelle Rear Glass

[OneStopRestoration]

Can anyone provide a secure source for 68-72 Chevelle Rear window Glass(tinted). I have ordered (2) from Pilkington pieces and at the bottom edge in the middle where the glass would seal against the car its not formed as a true perfect curve. It sags in a spot or two. Please see attached. I tried a third piece from Fuyao and it appears it will fit but instead of being concave inward to the passenger compartment like an original its convex outward. Any help would be greatly appreciated.