One header option that guarantees that you will get exactly what you want is to make your own. U bends and J bends are available in infinite sizes and materials and the 16 and 18 gauge stuff is easy to shape with aviation snips and it welds very nicely.
If you're a welder, or have someone available who is, making a set of custom headers is a fun project. And header technology is highly evolved so with a little research you can find header designs for whatever your intended use is. You can even add a fitting for an O2 sensor to tune your intake for a perfect air-fuel ratio.
My son was given these block hugger headers for the 350 sbc engine going into his '66 Chevy 1/2 ton and I made this exhaust H pipe for him from tubing he got from Summit Racing.
