[CR]Bianchi Specialissima/Competizione seat tube ID

Example: Events:Cirque du Cyclisme:2007

Date: Sat, 7 Jan 2006 19:22:54 -0800 (PST)
From: David Feldman <feldmanbike@yahoo.com>
To: classicrendezvous@bikelist.org
Subject: [CR]Bianchi Specialissima/Competizione seat tube ID

A customer brought an (I think) early 1960's Bianchi frame to me seeking a seatpost. There is a sleeve reaching from the top of the seat lug to @ 10-12mm below the bottom of the slot inside the seat tube. Inside diameter of this sleeve is 25mm. Was this a repair, or are all Bianchi frames of this vintage constructed in this way? I owned a Bianchi track bike many years ago and don't remember anything so unusual about how the seat post fit.
Any ideas?
David Feldman
Vancouver, WA