I am not a fan of block hugger headers, but I had them in my 59 Suburban and ran t hard. I had issues keeping the collector gaskets from burning out. (even with the deadsoft aluminum ones). I would print out some pictures and go to a wrecking yard and just poke around, looking at some different chevy manifolds. As suggested above, maybe swapping them side to side? My 588 2-ton, they ran exhaust out the top of the manifolds, through the inner fenders, and put stacks out the top of the fenders! It was a grain truck used on the farm though and they didn't want to catch the fields on fire. I am sure I would get pulled over if I was driving it around town here that way!
