if it was my jeep i'd get longer brake lines. the 4" lift combined with the added droop from the disco's could stress the stock ones. don't need your brake lines becoming your limiting straps on the front.
don't know about you but i like having front brakes. 
honestly you could get by with bending the hardline to rubber line bracket down some, that's what i did on my jeep but i'm only running a 2.5" lift, or we've relocated the brackets to the bottom of the frame and gained the needed length that way. once you have the stock swaybar links off to install the disco's try it by jacking one corner of the front bumper sky high and see what happens then go from there. 