Very cool!
With all of the improvements and the dimensional changes you have in mind, those are going to be a trick set of control arms. Do you plan to modify an existing lower control arm, or do you plan to build a custom one? I'm thinking that you'll build a new design, probably out of steel plate. That's what I would do.
I have a buddy who builds ultra trick ($$) high end off road race vehicles, and he builds all of his own control arms and beams. Absolute works of art. I was over at his shop a while back and snapped a picture of some stuff he had just finished welding. "Just a couple of simple brackets and and some limiter strap tabs", he said.
I love fab work, and I'm really excited to see what you're going to come up with.