If all goes well, Hanks will make a cameo in the film adaptation of William Saroyan's classic 1943 novel 'The Human Comedy', which also marks the directorial debut of Ryan, said the Hollywood Reporter.
Ryan, 52, will start shooting for the film next month in Virginia.
The actor is also in talks to executive produce the film.
Hanks, 57, and Ryan gave hits like 'Joe Versus the Volcano', 'Sleepless in Seattle' and 'You've Got Mail'.
Erik Jendresen has adapted the story, which is set in a small town in California's San Joaquin Valley in 1942.
The effects of the war are revealed as Homer delivers messages of love, friendship, pain and death, including one message that alters his own life forever. Hanks would play the boy's father.
Hanks is all set to reunite with Steven Spielberg for an untitled Cold War thriller for DreamWorks and 20th Century Fox.