RE: flex shaft length on a rebuilld
If your using a square collet then you will need a cable/stub shaft that will allow you to cut and solder it. Not a huge deal but certainly more involved than just cutting a round cable. Another option - If your using an aeromarine collet then you may well be able to just swap your collet from a square ferrule to a round by just replacing the insert. Personally I would opt for the round cable setup.