I would like to look for a shaft collar like the one used in this photo of a cable robot:
As you can see, there is a flexure that clamps the collar onto the shaft (as a shaft collar does). In addition, there are two screw holes where the collar can secure to a pulley.
When shaft collar is typed into google you get an infinity of these, so clearly I don't have good search terms or the correct name for this type of component: