The first change of this type occurs on page 5, where the ducks learn that they have been shanghaied to the ruins of Sagbad. Scrooge in his anger makes a flying leap at the Swami, slugs him in the stomach, and Khan Khan has to take refuge atop a broken pillar.
In the published version, McDuck simply chases the Swami up the side of a pyramid. Using the pyramid at this point in the story constitutes a nice bit of foreshadowing, for it is the very place where the treasure lies buried. Page 15 of the shooting script refers to it as a "curious stone pyramid that has been part of the b.g. [background] all along."

On page 16, Scrooge tells Khan Khan to "Go to blazes," which must have sounded like swearing and so it got shortened to a simple "Wak!" The original final confrontation between Khan Khan and the ducks must have been too rough, for Barks' shooting script contains this marginal note - "Change to heli[copter] lift gag" (page 20).

On page 21, Barks kept within the pale of Disney taboos by not showing the actual moment of Khan Khan's death. Still, it contains extensive revision, softening the dialogue considerably. Barks' shooting script reads as follows (the numbers refer to panels):

5.	Swami becomes very wrinkled and aged. Kid points: "Hey! Look! The king is turning [crossed out: into an] old, old-" Swami looking toward open doorway. "My armies are dust in the desert out there!"
6.	Swami going into desert a bent, old man. Swami: "I go gladly to join them! Everlasting life, Good-by!"
7.	Don and S by treasure pile. Don: "Well! The one-time King exchanged this treasure for a handful of gray powder!" S in treasure bathing. "Yeah, after living forty centuries anybody'd be a nut!"
8.	Kids looking askance: "Maybe-or very, very wise!"

Note on published page 21 the change of "old, old" to "old-old," and the addition of "tired-looking" which help gloss over the withering of the Swami's face. Khan Khan's line "I've had it, as they say, young princes," with its touch of slang, lightens the dialogue even further.
Khan Khan's demise lasts only two panels in the shooting script as opposed to three in the comic. Another difference is that the shooting script has two panels in the last tier, instead of the long single one in the published version. Apparently Barks wanted to underscore the nephews words of the shooting script, which are different and certainly not as impressive in the published version.

In The Carl Barks Library - Set V, Geoffrey Blum writes: "Not having the sketch script, it's not clear tell whether other, more significant changes were made by Barks or by his editors before handing the script over to Strobl. Occasional marginal notes will hint at a planned revision, but in many instances Barks seems to have been satisfied with his first version. Where the effect of a revision is to soften the story's bite, we may be pretty sure that the editors had a hand in things."
About the alternate ending, Blum concluded: "This is certainly the work of the editors, who must have found the Swami's transformation and death too much like something from a horror comic."

Michael Barrier mentions that the story's dialogue in Barks pencil script is identical with that in the story as published. This seems to mean that the pencil script may have been investigated by Michael Barrier before it got lost.
If so, Barrier's information would mean that Barks himself smoothened and altered the shooting script version.

And why wouldn't Barks have made those changes? As with his decision to change a violent sequence into a helicopter lift gag (page 16), Barks could have decided in advance that the editors might not approve the tone of the original ending. Slightly restaging some panels and softening some dialogue, are much less rigorous changes than transforming a violent sequence into a harmless sight gag.

  Sources