@Spec, willys is correct in that I HAVE used all original mounting points including the two on top. I welded two smaller tubes intersecting the horizontal one. Inside each of those tubes is a shorter section if tube welded into place which creates a shoulder. This shoulder is the correct height to use the original allen bolts the stock rack came with.
willys, I've always wanted a good tubing bender for various projects but haven't been able to afford one... or three. I ended up building my own for the most common 5/8" .065 wall. I bought a Harbor Freight bender for 1/2" but not only is it made for copper tubing, it's radius dies are so sloppy with mild steel that they leave a slight distortion in the bend. I suppose that's "good enough" for certain rack applications but it still bugs me.