I'm not familiar with the script you mention, but my guess is it was abandoned because Sci-Fi treatments of Moby Dick already abound (most notably, "The Wrath of Khan"). I wish I could remember and point you to the reference where Bradbury discusses working with director John Huston on the film version of MD (the one with Gregory Peck, not the disgrace Patrick Stewart's Ahab was in on TV). Apparently, Huston was the Boss from Hell, and the two did not get along, but their collaboration created a masterpiece. Bradbury was able to condense an extremely long and complex novel without sacrificing the essence and spirit of the original material, and he captured the rhythm and flow of that Old Testament Yankee speech to perfection. I would recommend anyone who's lost a bout with Moby Dick see the film and then go back and re-read the novel. Bradbury definitely got it right, and the book will make much more sense with the film as a guide to its murky depths.