Bob Hanson asked about Carlton cable routing.
One possible answer as done on my parents' Carllton Catalina's was a guide for the rear cable atop the BB shell and a stop on the down tube about 3" above the BB shell, from there a section of cable housing guides the cable to the stop on a Huret front mechanism.
If a mechanism without a cable stop is retrofitted, a different set up is required, as seen in the detail image where the cable housing passes under the BB shell and between the chainstays to end without a stop.
John Jorgensen
Palos Verdes Ca USA