Your question is very broad. I think if you spent hours and hours researching all the different builds we have here and made your own list you'd be better off. As for the rear axle you can't go wrong with an 8.8 out of an X. Do a search on axle codes. Spring over axle.
There is nothing written is stone about which way to go. I've had D28, D35, 7.5, 8.8, D44 and D70 and now looking for D60. And about every suspension you can imagine and I still ain't satisfied.