A flip creates some axle wrap.... 6 inch blocks really create axle wrap, So i understand your need for a traction bar. However, i think it might be a better idea to put some of that time/money/or energy into getting rid of that tall block. It would really reduce the axle wrap. Try a set of 6 inch leaf springs.
But if you are still going fot a traction bar...I believe that you need to create a mount that is lower than the axle centerline. Also, the longer the bar, the better. (helps with articulation with a longer bar.)
But there are other schools of thought on this...such as the anti-wrap bar by Az-Kickin
Blake