what diffs are you running?
order up some brackets from claytons. they sell them for most diffs. the frame brackets are set up for a 4 link, and they sell a crossmember for the front arms. use Johnnyjoints. .250 DOM wall (I think) three link the front, triangulated 4 link rear.
i'm assuming you're running some big diffs. if you're just running a stock front diff and something small like a D44 or 8.8 rear then the off the shelf kit might be a good option. claytons does sell just the long arm upgrades.
either way its gonna be some big money