Not sure what you mean by a 'camshaft lever', but try breakers or here;
http://cgi.ebay.com/ebaymotors/1973-Suzuki-TS50-TS-50-REAR-BRAKE-PLATE_W0QQcmdZViewItemQQ_trkparmsZQ7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2em63Q2el1177QQhashZitem5acf30da5eQQitemZ390023141982QQptZMotorcyclesQ5fPartsQ5fAccessories