Just had a local spring shop do these for a Nova mono leaf 12 bolt:
3 1/8" inside-to-inside and 7 1/4" leg length (measured from the outside top of the 'u'). When installed, there is 2" of thread below the Cal Trac mounting plates.
Not the exact info you asked for, but might give you some reference for length.... -Al
P.S. I like the Camaro build pics.