I may be missing something here, but the first picture is of the centrifugal clutch, not the brake. I have seen brake/clutch combos, but they use a bracket. To me, the brake lever looks like the type that is used with a hydraulic master cylinder? But I guess it could be used with a rod that has a 90 degree bend on the end?
The Brake/Clutch kits I've seen use a cable though.
Brake/Clutch
https://ombwarehouse.com/band-brake-bracket.html
https://www.ombwarehouse.com/univers...brake-kit.html