I remember reading somewhere that in the original Brian DePalma film Eve Plumb was high up on the list. Melanie Griffith was also considered and was close to landing the part. Sissy Spacek was considered a long-shot and got the part because she showed up to her audition wearing an ancient, frumpy dress, no make-up and vaseline in her hair.
Chloe Moretz is, at least, the same age as the character and that's a first (16). They didn't give the part to a twenty-(and-even-thirtiesh)-something. Sissy Spacek (1976 version) was 26; Angella Bettis (2002 version) was 29. King wanted Linsay Lohan (26) to do it, but I think that might've been a trainwreck. Moretz also does seem to have a bit more, how shall we call it, "baby-fat" than the other two actresses, bringing her a bit closer to King's vision. Carrie, in the novel, was - as has already been pointed out - somewhat overweight (one of the abusive nicknames given to her by her bullying schoolmates was "puddin'"). She also had acne ("The Lord's way of chastising you," as her Mommie Dearest, Margaret, said in both the novel and both, I believe, cinematic previous versions). Regardless of the discrepencies between the written Carries and cinematic Carries, the producers stated that this version will be closer to King's story, albeit with updating (I guess that's why Margaret drives a car, but I still think, even in the twenty-teens, I can't evision it - I still see her huffing it on foot to the laundry and dry-cleaners where, in the novel, she worked). The 2002 version had Carrie researching her powers on the internet rather than in books in the library, causing Momma Margaret to spit the word out as if it was blasphemy: "The...internet."
I'm still dying to see this version. I'm a bit ticked off it's been moved from this past March to upcoming October. I want to see it now. But maybe that's necessary to try and improve the marketing; like I said, I'm not enthralled with the first trailer. It looks cheap and like something from one of the old slasher films from the eighties. The portrayal of Margaret particularly falls stereotypically flat. In the '76 version, she was over the top; in the '02 version, she was icingly subtle. But Moore, being an accomplished actress, will hopefully pull it off.
Gerard