That BB shell and bridge are different from the ones on my SBX but…it has semi vertical dropouts and I believe the earliest ones had a horizontal, at least looking at the US market indicates this.
the overall appears of the frame looks a lot like the ‘89 Sport SX but again they wouldn’t have that DT or dropouts
BTW is Bianchi engraved on the top of shell
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk