In these early discussions, Indy’s companion Sallah was supposed to have a young son named Sabu. He was slated to enter the temple with Indy, where he is dressed like Lawrence of Arabia (as George Lucas puts it), and holds up the staff in the sunlight for it to shine through and illuminate the inside of the temple.
This also involves the portion of the scene where The Nazi Flag drops down to rescue Indy. One can only speculate the reason why the character of Sabu was dropped, making his father Sallah more prominent. It can even be argued he was shelved and later re-tooled to become the character of Short Round in The Temple of Doom.
The staff is talked about many times in the story conference between Lucas, Spielberg, and Kasdan. Indicating it was indeed a major plot point early on in the development stage, and a factor that would lead to the discovery of The Ark. Which is, of course, the main objective of the film.
Another point touched upon is the pendant that holds the key to The Ark. The scene mentioned here The Nazis invading Marion Ravenwood’s bar in Nepal and try to take pendant with The Gestapo’s hand getting burned with the map of The Ark pressed on his palm. A scene that also condensed in the finished film.