The Fort St George was owned at first by the Adelaide Steamship Company from 1912 to 1921 and she was named SS Wandilla (she had two sister-ships named SS Warilda and SS Willochra). During the WWI, she was redesignated HMAT as she served as both a troop transporter and a hospital ship. She was returned to her owner after the war but the company decided to sell her to Bermuda & West Indies SS Company in 1921. She was renamed SS Fort St George and, as you said, collided with the Olympic in New York in 1924.
She was sold to Lloyd Triestino in 1935 and renamed SS Cesarea. In 1938, her name changed to SS Arno. She was sunk during WWII (September 10, 1942) by aerial torpedoes of the Royal Air Force.
Hereunder is a picture of the ship as the Fort St George :