There is a dicussion on a very similar topic in this General Tech forum listed on 9/22/99. It may be of some help. You can select the number of days viewed at the top of the page with the postings. In short, Hooker Super Competition in 1 5/8" diameter fit pretty well, but I've seen many 1 3/4" headers that had to be massaged to make them clear the steering box. I any way you look at it, headers will always be a challenge compared to cast iron manifolds.