Hi Brad,
I wonder if the owner has given some thought as to only taking down part of the barn - for example dismantling one bay and then reusing the salvaged materials from that bay to fix up the rest of the barn. That way the barn would contain all original materials and its pattern and place in the landscape would be preserved. Missing or lost bays is quite a common feature in old buildings. If this is a square rule barn then a degree of interchangeability should be possible.
I do appreciate your comments that the owner has the ultimte say but just maybe they are not currently aware of all of the options at their disposal.
It would be interesting to see more shots of this barn and then for the forum and moderators (especially R Christian) to provide some input and guidance to the huddled masses.
This cannot be the first time that this situation has been encountered,as your own personal experiences already attest and so presumeably experience based guidance is available from others (e.g. Charles Leik at
http://www.thebarnjournal.org ).
Regards
Ken Hume