Frank R. Armour Jr., 50, was elected president of H. J. Heinz Co., the first non-Heinz to hold the job since the firm started as a horse-radish distributor in 1869. He succeeds H. J. Heinz II, who became chairman of the board. Armour (no kin to Chicago's meat-packing Armours), went to work at Heinz in 1927 as a visitors' guide, held 57 varieties of jobs within the company. He worked in sales and advertising, became general manager of manufacturing in 1946, a vice president in 1949, executive vice president in 1957. Armour will be trying to widen profit margins; while fiscal 1958 sales climbed to $293,800,000 from $278,900,000, and Varieties increased to 675, net dropped from $10,600,000 to $9,300,000.