I know of three. Marv Berk in MO, Gene Hershey in VA, and John Clifford's. The original design is from Dennis Wiley (of Early Bird Jenny fame), but is now owned by John Clifford.
Here are a few pictures of Marv's. Marv has an O-200 powering his. Marv attempted to fly it to Dayton this year, but the weather got in the way.
Gene Hershey's SPAD was blown around by a UH-1 and is getting rebuilt.
Hope this helps,
rob