The Bianchi's not a bad bike. Shimano 600 is Ultegra level, so that was a pretty good bike in the day.
As everyon else has said, the modern bike is still going to be better.
Also how the hell does the shop have a number of 20+ year old NOS bikes. I'd worry about the fact they've sit unused for that time.
I'd buy the new bike, or offer the LBS $500-600 on the Bianchi.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.