Gary
When I wanted to keep the cables neat, clean and dry on my trail bike I always used a piece of inner tube. Ok so it’s not quit as good as Mr Hondas part but would do the job until you find the correct part.
I also understand you are looking for contact details of someone who can repair Speedo’s. Mechanics July 08 had an article on Chris Rivett Tel 01604 455160 Mob: 07917 365060 who they recommended.