Band brakes on rear wheels, or calipar brake on a sprocket just about the best 2 set-ups, and can usually be installed for under $50.00, a scrub don't work when it gets damp or wet, and the band around the clutch also gets so hot that sometimes the heat will break the bonding agent, that holds the brake padding to the band, a jackshaft brake can also be installed but then again if the chain breaks, you have NO brakes!!! Good luck & be safe.
dave