Well, first off, keep in mind that this was the 1940 PHANTOM that Crawford was considered, a full year before Chaney had become horror-star material. Universal had a long line of aborted film projects for the story, even leading up to the Hammer film, which started in pre-production as early as 1959. Crawford was picked as a replacement to the then unavailable Charles Laughton (who had acclaim from IT STARTED WITH EVE) to co-star with Deanna Durbin, Henry Koster was going to direct and Joe Pasternak was slated to produce. When Koster made his intentions known that the film would be a flat out horror, Durbin walked out on the project. Front office pulled the plug.

Chaney didn't lobby the role until George Waggner stepped into the picture (around the time he was making GHOST OF FRANKENSTEIN). By that point, I'm sure the studio had Rains more seriously in mind.