 Arko played at half-back in Manly-Warringah's first Grand Final appearance in the 1951 NSWRFL Grand Final against the South Sydney Rabbitohs at the Sydney Sports Ground.The day didn't go as planned for the Sea Eagles though as Souths ran out easy 42-14 winners.Although Manly were easily defeated by Souths, they gained respect around the league for having reached the Grand Final in just their fifth year in the premiership having joined in 1947 (fellow 1947 entrant Parramatta did not play their first Grand Final until 1976, a 13-10 loss to Manly).