Two more for the casting rondelay:
Lauren Ambrose, and
Megan Fox (who may come off a tad too slutty).
It has, also, been pointed out that in the coif-tech future we're living in, hair color is infinitely malleable. But while this "film" still exists only in our heads, let's keep it pure.
EDIT: Adding Laura Prepon—thanks, Alex!—who was a much hotter Donna as a redhead: