That is all well and good, but if the arms are worn/flogged to the point they no longer retain the ball joints then they are work hardened. It is more likely someone previous to you owning the vehicle stretched the arms or even over heated them with an oxy to get the ball joints in (probably couldn't get them straight enough and they went in crooked until they flattened out on the lip). Welding or even tempering these arms will end up creating further weak spots in them. By design the lower control arms take most of the weight of the vehicle and need to be 100% reliable to keep that ball joint centered in its correct position for both suspension and steering duty.

Seriously suggest you get another good pair and start again. Eight months ago I could have mailed you a good pair for the cost of the postage... Dang it...