To re-iterate my first comment, the idea came from people who apparently have done this. That's why I'm asking for more info. And quite frankly I don't care, at all, if one collector is two inches closer to fender or other is two inches closer to frame rail, as long as they both end up in place where I can continue the exhaust pipes. Idea is to keep them outside of frame rails anyway, ending in front of the rear tires.
You missed the word ideally. Naturally if such headers do not exist, then some work needs to be done. Framing of the comments on the previous thread ("_just_ buy Chevy headers and change flanges") gave me hope that there would be headers which would fit with sensible amount of work. And like the title says, I'm not looking for headers that fit _perfectly_, I'm looking for headers which fit the best :)