It's not a substitute for a clutch pulley, you will not achieve the same stall rpm that you can with most other clutches.
And the pads sit on a flat spring, so as the rpms go up the weight of the pad bends the arms out and engages the outer clutch bell. If you remove weight from the end then it wil engage at a later speed because there is less force pushing it outward. The problem is that's where the pad is located so the move you cut of the less pad you have, so you can only remove so much before there is no clutch. The other way around this is to add another pin close to the pad so you can keep pad but reduce the moment arm. Which is also a pain in the ass because the other side of the bell is another clutch surface for the starter clutch. You can try to weld t down but it ends up detempering the spring a bit. The distance from the pad and the outer bell is really small so it's hard to get it to not move that much. Even if you take the starter clutches out, cut almost all the pad of the arm, move the pivot point inward, and all that, it still will engage earlier than a puch 3 shoe with the springs run in.