You know, I understand that you have a need to solve this to your satisfaction, so why don't you do what I suggested and read Smith. None of this is going to make any sense until you do.

As far as the tubing material for the control arms, that will depend on the stresses the car will encounter. I built mine very heavy duty, so that I could drive up onto a curb and back down off the curb and not damage anything on the car. For the lower arms, I used 1" o.d., 0.188" wall chromoly 4130 with 3/4" o.d., 0.125" wall stiffeners. For the uppers, I used 7/8" o.d. 0.188" wall chromoly 4130.

Some builders have used thinner, smaller material while others have gone the other way and over-built like I did.

Again, I'm going to ask you to do something before you ask any more questions.....
READ SMITH.