First have not seen any of the fuel sender wires with a protective coating like normally found on oil pressure sending wires
Typically the fuel sender wire is retainer to the drivers side wheel housing (over the rubber luggage protective strip) with a wire slip on clip. Typically like the ones used to the tank support under the car though a few of the all plastic big S shaped one
Typically one or two strips of wide tape held the wire to the trunk floor on the drivers side as shown in the pictures and ..........
......one smaller piece of tape above the gas tank on the passenger side of the trunk floor. No J clips/retainers used.
From there the wire exists the trunk through a grommeted hole on the passenger side and is retained to the body (on the way to the sending unit) typically by two coated wire clips attached to the gas tank opening edge
Hope this helps illustrate the normal practices related to your subject for a late 67 San Jose built fastback