No you dont have to go with a resi shock. A fox or radflo emulsion 6" or 8" coilover shocks. For springs its probably best to get some dual rate spring harware and run a 10" spring with a 4" tender spring. You need at least a 750 or 800 pnd spring rate to get a good ride height and not have the spring start to sag out very fast.
actually you'd want a 6" tender..i'm sure that was just a type o sean

: you want the total spring length to be double the travel of the shock..so if you run a 6" travel c/o shock you would run ONE 12" spring, if you go 8" then run a 10" main, 6" tender combo...the calculated spring rate is as follows: (spring rate one x spring rate two)/(spring rate one + spring rate two)= cmb. spring rate(lb/in)
and an emulsion shock is fine if you want to save a couple bucks..unless you're driving it in baja you're probably not going to use the shock to it's full potential and fade it out...