Found information that metallic brake shoes were available at least from 1961 on passenger cars. Those 280 brake shoes are 11x2 (same size as 228 brake shoes), which are used on the rear of 1959 through 1970 full size Chevrolet cars, and the front of 1955 through 1957 Chevrolet passenger cars.
1961 police option metallic brake shoes
1963 through 1970 RPO option listings ~ J65 metallic brake shoe option