It may not just be the pads and pivots that is causing poor braking. Modern high quality teflon or plastic lined cable housings and coated cables can significantly improve braking performance by reducing friction in the braking system. The cable housings you have on there may be original unlined housings and potentially corroded or unlubricated. If the housings are unlined, you might find some improvement from simply greasing the cables where they pass through the housings. If they are teflon or plastic-lined (these should not be greased), the lining may have worn through in spots in which case they would require their replacement.