There's one wrinkle to all this that I need to go back and confirm, which might make the process of investigation easier:

If I remember correctly, someplace on the Web site Allen says that he designed and wrote the software he used to run the stylometric analysis...and that he was willing to share the program with anyone who wanted to check and/or extend on his work.

Assuming that offer stands, and presuming access to the necessary source texts, then I'd think that the hardest part of the job may be done (and now that I think about it, that Allen may have made a larger contribution to stylometrics in general than he may yet have realized).