The different seatpost diameter (26.2 mm) indicates that the seat tubes were different - unless they brazed in a sleeve to reduce the diameter. What did other Italian bikes in the 1950s use?
I think it is the downtube decal that makes them ride differently!
Seriously, you look down and see that classic decal, and you think:
"I need to go faster to do this bike justice." Unfortunately, when I
tried to test my feeling that my Cinelli SC from 1972 or 1973 was
faster than my race bike (Marinoni Columbus SL, Campy SR), and
entered it in a time trial, this was not borne out by fact. Of
course, I also had not been training due to an accident, which had
put my normal racing bike out of commission in the first place.
--
Jan Heine, Seattle
Editor/Publisher
Vintage Bicycle Quarterly
http://www.mindspring.com/