I just pulled these out of my 1972 Firebird where they were mistakenly installed around 20 years ago. (Firebirds use a 4-leaf setup with a much flatter arch).
They had zero miles on them when the car was put into storage back in the 1980s. The are a 5-leaf spring, part number 21-339 which translates into a 70-79 Nova, V8 "heavy". You can see the actual specs for the springs right here:
http://www.stengelbros.net/21-339_p_2847.html
They go for $188 a pair new. How's $50 sound? I'd prefer not to ship since that would probably double the cost. Pick up preferred in Central NJ. Thanks, Steve