I would very much doubt a Bianchi would have French threads. Italian maybe, but probably not French.

Carefully look at the bottom bracket without the cranks to see if it lists the threading. You may have to remove it to verify.

Many of the early bottom brackets were off-center. Make sure it isn't installed backwards. I'm not quite sure of the reason for that, but I think some cranksets were made specifically for off-center bottom brackets. So installing them on a symmetrical bottom bracket would be problematic.

From your photo, it looks like the inner ring is closer to the chainstay than the outer ring. As long as nothing touches, it may be ok. Or, perhaps cranksets with smaller rings?

Where are the ends of the cranks, near the pedals with respect to the chainstays?