440 under car headers need advice.

Then let me try to enlighten you.:rolleyes: This board (and others) are full of stories of people who ponied up and bought the high-dollar headers, and still had trouble making them fit, and had to beat on them. The problem is that body & frame, and engine placement, tolerances often exceed the minimal clearance available in a BB A-body. And production headers are not custom-massaged for those inevitable differences. A point also recently made here and elsewhere.
Also, not everyone has your assumed John Force-sized budget for their play toy. $800-1K for some people IS a big deal, especially if they're putting the project together one piece at a time as money permits.