Change Project Type after editing? (frame rate)

Hi guys,

well have finished editing a project only to discover that I set the project settings incorrectly, to 1080p 29.97 when all my footage is 1080p 25. Video mixdown now produces a weird frame-blended problem with any motion, like this:

http://c2.avid.com/forums/p/124909/716328.aspx#716328

that looks horrible. So, all I have to do is change the project type to 1080p 25, right? All the footage is AMA-linked Prores 422 1080 25, so surely shouldn't be a problem? Except that this option is no longer available on the project type dropdown in the project window/format. The only options are: 

30i ntsc

720p 29.97

1080p 29.97

1080i 59.94 

Help please!