No body panel expert here but that panel sure does look kinda ugly. Looks like it's got a lot of rolls and that bugger weld in the middle if that's what it is. Is it possible it's the fenders? Maybe try a salvage yard to see if you can find any decent body panels, you know they will fit that way and most likely be gm parts.
Also, a c10 4 wheel drive is a k10. The C denotes 2 wheel drive and K denotes 4 wheel drive. C 10, 20, 30 & K 5, 10, 20, 30. K5's are Blazers and Jimmys only.