the Campay 626/a clip may not work for him because of his pumps location. He'll probably need the wire to be more inboard, so looping under the BB shell, with or without a guide or cable loop, and up between chainstays may be his best option.

When I work on classics like this, I prefer to use some housing because it makes the stop seem functional, and avoids the choices of skipping it entirely, or threading through it and having a sharp bend in the wire leaving to go below the BB shell.

The elimination of the FDs housing loop was an evolutionary process, that started when enough riders individually found that the BB shell made a great "pulley" and started rerouting the wire that way. What made this possible was a change in FDs to actuation arms that pulled down. On many earlier models the wire was tied off to the body, and the housing connected to the movable arm which moved up, and therefore needed the flex.