I would bet the unbent line was for replacement use only, the original was likely pre-bent steel. You wouldn't have time on the assembly line to bend and fit lines as the truck moved along the line. Compression fittings don't seem right either, not sure I have ever seen a factory compression line other than the 1/8" brass oil pressure gauge line.
I have purchased a a number of Carter Carburetor cores and all of them had inverted flare fittings for the fuel line.
The rubber lines are for flex joints such as engine to frame, and tank to frame.
