Pretty bike, Speedy. I've always had a soft spot for those Celeste Bianchis. Plus, it looks like a
bike, as opposed to some of the carbon fiber monstrosities out there today. Steel is real! That being said, I just did a quick search on one of our distributor's website. (I'm in the 'biz) It looks like you might be SOL unless you really want to upgrade everything.
First, 144mm bolt circle cranks are largely a track/fixie thing these days, so the smallest chainring I found was 42 teeth, and that was for a 1/8" chain, not the 3/32" that you'd need. Also, looking at where the bolts sit in relation to the teeth on the chainring, my guess is that you couldn't get down to a 39t on that bolt circle. (Part of being "in the biz" includes the design and manufacture of cranks and chainrings, so I have a pretty good hunch here
)
Second, they didn't even list any six speed cassettes, let alone Campy ones. I'm assuming that your bike runs indexed shifting, so you'd be stuck with six speeds unless you wanted to (if you even have the option) run friction.
My original suggestion would have been to run a 39 tooth front ring, and a 12-26 or 11-26 rear cassette. Neither of these options appear available, at least not new.
I'd just leave it stock, and buy a newer used bike if you really feel the need for speed. A budget of $1000 really isn't that bad if you scour the used market. Besides, think about how pissed off the other riders get when they get passed by a guy on a 25 year old bike!
