If you're looking to go clear to 31" tires, you'll probably need to install either the body or spacer lift too. With the body lift and just the Eibach spring lift, my 31" tires are real close during full compression.

As far as shocks go, I've gone with 1" longer than stock shocks, and have had no problems. I get full travel in both directions, but another inch down would be nice too. 3 - 4 inches is a little long unless you're also adding the spacer lift.

Logansportage

White 1998 4 door KIA Sportage 4x4 w/Eibach 2.5 spring lift and TJ rear coils, 4crawler 1.5 body lift, Monroe Sensa.trac shocks, Bosch 4+ plugs, Eaton LSD, 31x10.5x15 BFG KM tires, 2.5 cat back exhaust w/SpinTech muffler