Don't know where to go to from here then. My four bow from Legendary (IIRC) was spaced properly, but I had the advantage of having my old headliner to compare against.

Sorry I can't help more.

Did the 6 bows you have come with the car, or did you acquire them after-the-fact? I assume from your sig that you're pretty familiar, so you'd know that it is a 6-bow car, not a 4-bow.

Maybe someone here with a 6-bow 71-74 B-body can provide you with measurements of the bow sleeve (seam, in this case) spacing on their car. That might provide a clue. Since my '72 is a 4-bow and the only one in my stable, I can't help there.

Good luck.