It's not that expensive to get custom leaf springs made...

edstorm: With a custom pack, you can make them stiffer with a nice progression that will withstand the extra weight without having them lift the truck any.

I know a few folks have had custom packs made... where did you get them done, how do you specify what you want, and how much did it cost?

ETA: This is all about the REAR leaf springs. Your front springs aren't 'springs' at all (at least not like what you're probably picturing). They are torsion bars (a metal rod that gives a springing-action when it is twisted). You don't need to upgrade or modify them unless they're broken. They can be easily adjusted if you need more or less tension on them.

Shocks are a VERY easy install-it-yourself item BTW.