Unfortunately, the careful laying out of the philosophy will not play well on screen. If I were writing the screenplay, I would focus on three main premises. Then I would immediately back them up by leveling a charge (accusation) then response (action). I would make my examples contemporary. There are enough examples in the speech already. Much in the speech is restated several different ways. No need for that in a movie. I think it's essential the actions come off strong and in stark contrast with the government's cowardly actions. But the people need to be accused. I would not include any sections discussing God or religion. If you consider the other two movies, it's best to focus on other major themes. You do not want to turn-off a significant part of the viewing audience before they read the book.

Rand repeats herself over and over again throughout the speech. Cut the unnecessary repetition. Show flashbacks of how things fell apart as Galt goes through his spiel. Rely on this type of visual stimuli with a well-read voice over.

One of the best reasons to incorporate scenes from the previous movies into the climatic Galt speech (beyond tying it all together) would be to promote interest in seeing the first two movies. Ca-ching.

I would begin the speech just like in the book. In the room with Mr. Thompson, Dagny and everyone else. I'd then fade to people all over the country listening to the speech. Where Galt tells his story there should be flashbacks and finally in the essential, most important points we should SEE John Galt delivering the key strokes ! Just my opinion.

Very similar to the way Howard Roark’s speech was play in the movie version of The Fountainhead. cut it down to the essentials and show the speaker giving it. I know Galt's speech is over the radio in the book, but a shift to on TV and and a little editing would make it work well in the movie. It is too important not to have it in the movie. But then, The movie is already shot so this is a moot point, right?.

I would make ONE point: I am not your milk cow. I will not be robbed by those who view me as a serf that must obediently produce so they can reap my production and distribute it as they see fit.

It explains JG's actions at 20th century. It explains the strike. It explains Francisco's speech. It will hopefully explain Ragnar's actions in part 3.

Seriously - one point. Make any more than that, and I think the typical audience won't absorb it.