The bulge under the E brake cable is factory. You could put a slice in it, beat it flat and weld it up. On my duster I used 2x3 . At the rear, rather than cut into the rear floor pan, I cut out a 1/2 tall strip lengthwise making it a 1.5x3 in the rear floor area and welded it back together . I cut it with a curve so it made a nice transition at the rear pan. Cardboard templates are your friend with this kind of stuff.