The standard vs. Italian issue involves the threading of the frame, not an issue in your case. Actually, newer Bianchis use standard threading, not the oddball Italian size.

See: http://sheldonbrown.com/cribsheets/bottombracket for details on this.

If your frame is a Portage, it was made for 584 mm (650B) wheels. The Alyeska, I believe was for 630 mm (27 inch) wheels, but might also work with 622 mm (700C). Borrow some wheels from another bike and try them for size.

See also: http://sheldonbrown.com/bbsize

and: http://sheldonbrown.com/chainline

and: http://sheldonbrown.com/fixed-conversion

Many cyclists interested in simplifying consider going to a singlespeed freewheel as a way to "test the waters" with the idea that if they turn out to like that, they might later convert to fixed gear.

This is generally the wrong way to approach it, in my opinion.

I STRONGLY recommend starting out with fixed gear. If it turns out to be a problem, you can easily convert to freewheel later if you want to...but my bet is you won't want to if you give fixed gear a good try (typically takes a couple of weeks of regular riding to get past the strangeness, but then it's quite addictive!)

Most folks who set up their bikes with a fixed/free flip flop wind up using the fixed gear side pretty much all of the time. The freewheel option is mainly useful for when you have taken a longer than usual ride, and need to get home even though you're all tuckered out.

Sheldon "Fixed Is More Fun" Brown