In order to do 6" correctly there are 2 routes. Long arms or drop brackets. I have run both types of suspension, and both had pluses and minuses.
For around the 800 dollar mark,
RE Drop Brackets. You will need to fab your own drop bracket supports as the ones RE sells wont work with the MJ upfront.
RE HD trac bar and mount
Rusty's 6.5 springs
DT3000 shocks 28", with JKS bayonet eliminators
Crown front brake lines 30"
For the rear you will need some SOA perches, and a 30" brake line
You can use your stock upper and lower control arms with the Drop brackets and have zero issues. I do recommend welding some plate on the bottom sides this will stiffen them and prevent nasty things from happening.
I ran that very setup till I went to Terra long arms. Some ppl say that Terra Flex upgrade LA kit isn't worth a poo, but I have yet to see what they are running
Yes it uses a parrallel 4 link, instead of the radias arm setup. both setups have pluses and minuses.
BTW I used all the same parts on my rig still except I am running LA's now