If you want to replicate original, go to the '32 parts book--the late one is readily available from the parts dealers--and go through the spring leaves one by one, cataloging what leaves go in each type of spring...obviously, you'd start with the sedan one on the assumption that is correct and complete. You will likely find that there are different leaves within the pack that aren't used in both quite aside from the different numbers...leaves vary in thickness as well as length. If you are lucky, everything might match up using leaves that are in the sedan pack. The list of all the leaves will require charting and some aspirin to figure out.
If you are just seeking a softer spring and are not worried over whether the third leaf is the correct one, one factor is not to leave big differences in the lengths of the areas not covered by the next leaf above...if you discard such that there is a long unsupported area at a level in comparison to the others, that becomes a sort of hinge point in the spring and it will flex more at that point rather than compressing equally over its whole length.
