Peacock - One of the watchers of this project has been pressing me to rivit on brake pads just like you suggest. Since the clutch plate was the last operation, I decided to utilize the friction material with as little effort as possible. I think I could still cut up the piece and rivit it on. If it keeps working as nicely as it has so far, I don't think I'll mess with it.
Originally, I was planning to put a brake on it but never worked the detail out. I even faced off the front side of the rotor that is fastened to the crankshaft. Even though, the brake rotor assembly is pretty heavy, the machine doesn't have enough flywheel effect to keep turning when the clutch is disengaged like a tire hammer does. When I let off the clutch it stops. This may be more of an issue if I speed the power hammer up.