"I am approaching the project from the (Richard) Attenborough school of casting. There will be many big names from both Bollywood and Hollywood to draw audiences in," Shah told the Daily Telegraph in comments published Tuesday.
Shah, who last directed the low-budget "Hard Rock Zombies" for the American market in 1985, said he is in talks with acclaimed British actors Albert Finney, Helen Mirren and Emily Watson and Hollywood stars Tom Hanks and Tommy Lee Jones.
The big-budget two-parter is due to start filming in April next year in India, Britain, Russia and the US, he said.
Dixit told recently that although Shah had approached her for the role, "nothing has been finalised. We're still in negotiations".
She added: "My decision would depend on where it would be shot and how long it would take to shoot the film. Also, who are the other actors in the project. The casting is very important. Because one would want large sections of the audience to see the film."
Shah described the film as "the project of my life, both in its scale and the subject".
"I have been working on the script for over two decades and it is simply a story that has to be told. It took me years to find a way into her story, but I found it with her role as a mother - both to her family and to a nation with its teeming millions. Indira was India," he added.