Hi Richard. One of the great joys of the internet for me has been getting in touch with my heroes of days gone by. I've been coresponding with Erik Darling for four years now, and we even got together to do some pickin' together in Cleveland a couple of years ago. I believe the two twelve strings ehe ordered from gibson were tuned D to D and the stringing was normal (with the octaves etc.).....but fortunately I can now check with the man himself.
Your friend refers to a Sigma as a Martin???? Hmmmmmmm this 'rare find' may not end up being as rare as we're hoping, ha ha!