Originally Posted by desconhecido

Best I can tell, with a Campagnolo square taper spindle, there are at least 4 possibilities for each spindle length. Either the bearing surfaces are spaced for 68mm or 70mm BB shells and for each there is a spindle designed for either thick or thin cups. The difference between the thick and thin cup spindles is 5 mm in the distance between the bearing surfaces 49.5 mm for thick cups and 54.5 mm for thin, for 68mm BB.

So, if you are comparing a spindle for a 68mm BB to one for 70mm BB, the distance on the right side, from bearing surface to spindle end, will be 1mm assuming same spindle length and cup thickness and symmetry.

You seem to have a bike which, if I understand correctly, has a BB shell which is 1.5 mm shorter than it "should" be with Italian threading. With the same fixed cup, the difference in chainline between spindles of the same length, assuming identical symmetry/asymmetry, will be 1mm. The difference in left side crank arm position will be about 2mm. Which selection would match your situation depends on how, exactly, your bike differs from the "normal" Italian BB. Is the 1.5 mm difference symmetric or asymmetric?