Hi Donnie!
Condolences of the Gumtree Audax is...gone. That past, I'll be happy to keep an eye open for anything that might suit for you.
As for sizing, in my traditional horizontal top-tube tourers, I take either a 58cm or 60cm...and I'm the same size as you.
I'd guess something that fit me would come pretty close for you, but I would still suggest taking measurements according to Thorn's instructions (listed in their brochures) and making a call or dropping an email their way for confirmation what "should" fit you. Also, you may wish to take a look at Thorn's setup/positioning guide -- the best in the business in my opinion:
http://www.sjscycles.com/thornpdf/SetUpHiRes.pdfMy Sherpa Mk2 (which fit perfectly) was a 560S with 120mm stem and Thorn's anatomic drop 'bars. My Nomad is a 590M (no "S" model available, so the Medium top tube was the shortest for use with drops) and also fits perfectly...with a 60mm stem and compact drop handlebars. Comparo pictures showing how my bikes all fit me are posted here:
http://www.thorncycles.co.uk/forums/index.php?topic=4523.msg22089#msg22089I hope this helps a bit in narrowing down the possible sizes, Donnie. Best of luck to you, and fingers crossed at this end for a good outcome soonest for you.
Best,
Dan