Wouldn't the ball joint have to be relocated, not just the angle changed? With the proper fixtures though, your proposed process would be relatively easy and have minimal knock-on effects. Fewer risks too since the integrity of the arms is retained.
If you're going to this trouble, we just chopsawed the end of the control arm off, weld a flat plate with a 4 bolt chev ball joint thru it.
Support and gusset as nec.
It'll look fabbed, be strong as hell, and ball joint attitude/location is totally up to you.
Just saying, - that's what we did a lotta times.
