*Bottom Bracket: Italian 68 mm.
*Dropouts are 1st Generation Campagnolo Gransport with 4 mm adjuster screws. These dropouts were produced only in about 1950-51. This may have been because the oversized 4 mm shoulders were vulnerable to breakage and the Derailleur hanger had an impractical 4 o'clock position stop, as illustrated in a set in the last foto. This Colnago derailleur hanger was removed, unfortunately.
In 1952, Campagnolo updated the dropouts with smaller 4 mm shoulders and ultimately with a 7 o'clock derailleur hanger stop.
Top pics show complete bike with Universal Extra Brakes, Campagnolo GS Hubs, Simplex Derailleurs, Brooks B-17, Ambrosio Champion Bars Stem, Sheffield Sprint pedals and Magistroni cranks with Simplex rings.