The Ford radius arms (which you have modified versions) are designed to be parallel to the ground when under a stock late 70s ford truck. When you lift the truck and angle the arm downward, the coil bucket goes with it. and since the coil is bolted to the bucket, the base points forward and bows the coil. My solution was to make a pair of steel wedges the lean the coil bucket back. Wasn't especially hard or expensive. I had a local shop cut 2 steel bars in half on their big bandsaw and then I drilled the holes. and in case you're wondering how I bolted that up, the cut bar gave me 2 wedges each, with matching angles. one went under the coil bucket, the other got trimmed to size and went inside the bucket so that the bolts had a flat place to tighten down on.
lower wedge:
upper wedge:
before wedges:
after wedges:
That lean you're experiencing might be due to improper tightening of the radius arm bolts (the ones that pull the 2 halves together around the axle). If done one side completely and then the other, the arms can twist your truck to one side. somewhere online I saw the proper procedure for that spelled out. haven't needed it in years though, so I'd have to hunt it down again. make yourself familiar with some older ford sites. I like fullsizebronco.com also jeffsbroncograveyard.com has lots of useful parts for sale.
also, in order to get any decent flex, you'll want to cut off the stock lca brackets to get them out of the way and dump those poly C-bushings for some old rubber ones. but after you do that, you'll need to get the bumpstops properly positioned to get from eating the fenders or shocks. they'll need to point to the side slightly to keep from hitting the coils and to hit the coil bucket squarely upon compression.