Now that it appears you're not locked into your original idea I would add that if it were me I'd go for a spring with more leaves relative to spring rate (meaning if two springs were each rated at ~1200#, one a 3 leaf, the other a 4, I'd take the 4). My rationale would be that I'd have more "tunability" with more leaves, and likely a more compliant (or more progressive) spring even without any changes.