I ordered the wheels from Champion...
http://www.cwibeadlock.com/NBL%20Speed%20Series.htm
Rears are 15x10 w/5.0 backspace. Someone in the past had welded the spring perches in the wrong positions shifting everything toward the driver's side...I will have to run a 1/4" wheel spacer behind the passenger side wheel to clear the lower shock mount. We will run it this way this season and probably replace the housing next fall.
Both my partner and I were so impressed with the wheels he plans on putting a set on his '66 Nova. What I really like is how Champion offers it's wheels in 1/4" increments for backspacing.