I would suggest doing up some upper links for the rear end so its like hybrid of a 4 link and leaf spring. As it sits, you are going to get mega twist in those leaves, especially with blocks. In an old Corolla, I was running 2 in blocks with springs about the same thickness and number of leaves, but only 40 inches long, and I got almost 20 degrees of pinion angle change under load! It was absurd. I took out the blocks and rearched the leaves, and that helped quite a bit. Of course, you could make a pinion snubber, but they tend to make things behave unpredictably, as do traction bars. I don't want to sound negative for my first post in your thread though haha, the fab work is most impressive, especially those cnc parts for the front end!