coilovers, stock suspension, different k member?

Stock k-member weighs 35 lbs. You won't save much there. You're going to spend a lot of money to gain little to nothing, in my opinion.

Rack and pinion steering, abilty to swap most any type of engine by changing motor mounts only, makes oil pan a breeze to remove and provides more clearance for aftermarket pans. Those are a few reasons people buy them.