all the previously posted suggestions are valid. start from the outside in. it will take some time but as you work through the whole suspension/steering system, things will start to tighten up.
i still have the shackles and spring pivots to work over but after replacing the king pins, restoring the drag link, checking the backlash and adjusting the toe in, it tracks really well down the street (even with bias ply tires). it works well enough that i can "palm" the steering wheel when making turns even at slow speeds.