03 Model the Ready-Lift Set-up is a good choice IMO and if I remember correctly comes with a steel adapter for use with your service kit clamp. No Requirement to add longer shocks however just because I have not had any probs but like Dave said it is a good idea, as this kit does raise the front 2 ". Some cheasy kits have little brackets that add onto the shock, the ready lift does not, and are Forged.
I do plan to add them later (longer shocks) and I didn't cause my shocks were then new at the time 18K more until due and then I can Brand Match to my 0-4 lift Rear Ranchos.