It sounds to me like you have taken Corvette pieces and adapted them to your Olds frame without having a well-thought-out plan. If you have the control arms attached and are just now beginning to think about the rack, I know that you haven't done any planning and that you know little or nothing about independent front suspension and steering geometry.

I have no answers for you and I doubt that anyone else on this board will either. You need to do some heavy reading and educate yourself before going any further. Otherwise, I can see your Olds sitting out front a few weeks from now with a For Sale sign on it because you can't get the bumpsteer and evil transient handling response out of it.

The best way to do what you're trying to do would be to graft the entire front clip from the Vette onto the Olds frame. You would use the Vette steering rack and everything would be correct in relation to everything else.