The road spindle for a pre-78 68 mm BB was 112 mm, marked 68-SS-120. Sutherlands says that the Nuovo Record cups were thick, rifled, describing this as aluminum with steel insert I don't know about that -- I have a 1984 NR BB on my bike, and it's got thick, rifled cups that are all steel, I'm sure. For pre-78, thin cups were used for (old) Record, and Gran Sport.

It's on pages 3-29 ff. in Sutherlands, which you can download here:
http://icelord.net/bike/

If your cranks are d'un certain age, and have been installed and removed several times, they might benefit from a bit longer spindle, assuming that you want to have the center between chainrings on the 42.5 mm chainline. The later road spindle (like mine) is 114.5 mm, and I believe they added 1 mm to left, and 1.5 mm to right; but you could check that in Sutherlands too.