With the amount of positive caster that you have, it shouldn't wander at all. What concerns me is how you posted the toe spec "-1/8" I hope that this is toe-in. Your alignment specs are just like mine. I have absolutely no wander at all. The steering effort is increased with this caster setting, but that's it. This is with manual steering and a "special handling" 16:1 steering box.
Do you have power steering? If you do, you may have the wrong Idler Arm installed. The power steering Idler arm has a solid rubber bushing where it mounts to the center link. The rubber flexes as you turn and returns to its original shape when centered. This assists in recentering the linkage and also helps to stabalize the steering linkage. The power steering control valves are very sensitive to actuation on these old systems.
When installing the solid bushing Idler Arm the steering must be centered when tightening down the solid bushing to the center link. If you don't it will cause the steering to pull in the direction needed for the bushing to relax.
The manual steering Idler Arm has a free rotating bearing at its mounting point at the center link. The alignment geometry and the drag from the unassisted linkage recenters and stabalizes the steering. Steering effort would be greatly increased if the solid bushing, power steering Idler Arm were to be used with manual steering.
I would check this out. At this point you've got nothing to loose.
The reason that there are so many 17" wheels being used, is to clear the control arms on the front. You can use the stock suspension system. | 
