Just like to recommend a leaf spring source to the group. American made quality, yet priced very reasonable. I looked high and low for a source, and this company was very knowledgeable and good to work with. For example, the gal at ESPO has more knowledge about Mopar springs than most guys. Her usual guide line is 3400, 3600, 3800 lbs car, + ride height. She can also add 1" or 2" raise in ridge height. Also add a spring to the right side for Super Stock. http://www.springsnthings.com/leaf-spring.htm
Another good one is Babcock out of Milwaukee Wi. I needed leafs for the front of my 1931 dodge and they had the original blue print turns out they made them for dodge in 1931.