I would pull the car apart and get something flat and make sure all your bulk heads and chassis are straight. Check all your pins and arms for bent bits and holes that are too big and make steering loose. If there are lots of problems here then there is only so much you can do. I heated my front left bulk head up a touch by boiling it in water and then put it in a vice between 2 sheets of steel to straighten it up a bit. Not exactly straight but close enough. Just make sure everything is tight when you rebuild and make sure that when you tighten up the chassis to the bulk heads they aren't inducing tweak. Then follow the steps as shown earlier in this thread to adjust the tweak that is left in the car. I don't think you can make these old girls perfect anymore unless you've got a heap of cash to throw at NIP parts or can pick up a heap with a roller in a deal on the forums.