Rick,
I recently purchased a used Alvarez and had it modified in Lead Belly format. The bass E I believe is only a 57. My intent was to tune it to C, but it sounds more like Lead Belly when tuned to B. I think I've already talked about my theory that tuning to B simplifies coordinating with a harmonica played in "cross harp" in one of the two threads listed above.
Speaking of which, I did not get the first link right. For a discussion of 12 string tuning click here.
Roger in Baltimore