67 dart convertible trunk torsion spring length?

Pulled my original '67 Dart Convertible spring. This is definitely original to the car since I've had it since 1989 and it was on the second slot at that point and the color matches the car. So I see 41 1/4" total length. You've probably been over this before or even seen it work but it looks very likely to me that the 42" one would work. I would definitely take the chance on a pair of 42" springs.

I'm wondering though: does anyone know where the ones I see on classicindustries.com for the later years were made? It would be great if we could get them to do a run to fit these convertibles.

trunk_spring1.jpg

trunk_spring2.jpg