Check out Mountain Offroad i know its a site for jeeps but i'm sure their track bar will work on your fj. i have one on my jeep and solved all my problems. We fabed up a crossmember for it and used 2 jonny joints and a shackle that came with the kit up front and on the axle used the parts that...
i am running a 60 and a 14 both both discs and don't have any problem stopping with all stock components. But my buddy has a corvette master cylinder in his cj5 with 60's front and rear and discs and his stops great too. maybe that will work for ya