here's a couple for what it's worth with a straight enough edge 4' piece of 1" al angle..
blue is 72 k1500 original body and paint..
primer is 71 k20 original body sanded in rusty primer
both fairly flat front edge of door jamb to about 3' back and starts to taper in towards the rear lamps..
my layman opinion it's fairly straight and flat along the sides fairing even with the doors and narrowing down slightly toward the rear..
ignore the troll in the back of the blue one
hope that helps and good luck!
