The vast majority of high quality road bicycles from the 1950's through 1970's (especially Italian bikes) used a stainless steel "spring" type housing loop for the rear shift cable housing.  These were also popular in longer lengths for bar end shifters! Exactly what you need to finish your vintage restoration! 

NOS Campagnolo #622 Steel Coil Derailleur Housing

package comes with 5PCS

Stainless Steel