I have a 79 CJ7 and the curve is factory from Bestop. Also, my Bestop bikini front edge has a 3-piece metal bar that hooks into the channel. On each side (drive & passgr) the metal bar is about 1-2" long, that fits into the curved area, and the middle piece spans the distance in the middle.
Never tried to use mine with the hard-doors, so can't help you there.
Hope this helps with the "curve" of the channel.
79 CJ7, 3" Lift, 360 V8, Edelbrock Performer Intake, Comp Cam, Holley 650 Truck Avenger, Hedman Headers, Moser Axles, Herculiner, Warn M8000i, 33" Timberlines
Guaranteed to Make $$$$ with your Computer! No Risk Involved! Simply press shift-4 four times in a row.