There's nothing peculiar or different about an Italian bike than any other vintage bike when it comes to a 650b conversion. The main thing is you really want to be able to fit at least a 38c tire to make it worth your while. Also if much smaller than that, the bottom bracket height will get smaller and this may be an issue. The overall diameter of 650b x 38c is close to 700 x 23c.
This is a good description of what you should be thinking about before doing a conversion:
https://www.bikeman.com/bikeman-blog...sion-guidlines