What I do with the cable is to have a little "joiner" made. It's nothing more than a piece of 1/4" circular stock, say 60mm long. Drill a 5mm hole into each end to a depth of 28mm, then drill a 2mm hole through the 4mm centre that's left. Then you can add a length of outer sheath and replace the centre cable entirely with a longer one. Much easier than making an entirely new assembly. I use a length of electrical heat shrink to seal up the join which ends up neatly behind the coolant bottle.