Since you're a frustrated novice, my recommendation would be to buy an intake and carb that match each other and your engine. I'm not too familiar with Bianchi bikes but I'm pretty sure they have Morini motors on them?
Figure out which motor you have: https://www.mopedarmy.com/wiki/Morini_Moped_Engines
If this fits, just buy an intake for 15 SHA and a 15.15 SHA carb and you won't have fitment issues and you'll have upgraded: https://www.treatland.tv/MLM-morini-M1-15mm-SHA-intake-p/mlm-m1-intake-539.htm
My two cents