I'm not sure, unless you could be able to get to the server and see possible options with different NLS settings for Export.

Otherwise, You can try importing this if you have 8i installtions and play with it exporting with different NLS settings and see what helps.Here all I'm saying to you is trial and error if you can't seek help from Oracle on this issue.

Whichever is faster, read few more docs from metalink to figure out the issue OR T&E to figure out yourself.

Always big head ache with this NLS settings and character set conversions and lobs :(