Hello Peter,
I understand that a gentleman named Peter Collings was working on a sample set of Birmingham Symphony Hall as a project a few years ago (it would have been in Hauptwerk v1 format at the time - around 2004-2005):
http://www.petercollings.com/organsoundarchive.htm
He hasn't (yet) released the results publicly, so I'm not sure if he actually finished it.
It might be worth contacting him first, to make sure you don't unnecessarily duplicate work.