Hi Listers,
Thanks so much for your help. I have found the missing piece for the 1960 Bianchi! Thanks to all of the members of "Dale's Garage." Also, thanks to Bob Freitas for his generous offer to use his seat tube reamer--but I'm pretty sure it is 27.0 not 27.2 needing reaming.
Stephen Bryne
San Buenaventura, CA, USA