This segment follows the historical alignment of the pass road. Calling it paved is generous as it apparently hasn't been maintained in quite some time. You may also find that the path is littered with fallen rocks, small landslides, and organic debris. But the route is quite passable, and all this makes it more fun on the mountain bike anyway.
Parts of the road are carved as a sheer cliff into the side of the mountain high above the Brenno del Lucomagno Creek but far below the surrounding 8000 ft (2500 m) peaks. The guardrails on the cliff-side of the road have disintegrated in some sections so there is nothing to prevent you riding off the cliff (although the remaining guardrails are too short to be of any use). In any case, the roadbed is quite wide, so you shouldn't have any issues with the cliff. Enjoy the views!
At the end of this segment, if you're following the Gotthardpass Section II
route, you'll have to make a very sharp (nearly 180°) turn back onto the main highway for a short distance to the beginning of the Camperio