Attaching the tonneau cover to the rear seat upper

If my memory serves, a straight stick of generic welt channel did work on a members early a-body. This 67 and later seat back has a radius. Channel forms dont bend easy. The welt C could distort. Generic, aluminum or PVC, for this application is a gamble. I'm not a gambler. I would drive the car without the boot until the correct parts come. @barracudakid is the one to watch for these hard to find fish nuggets.