Why not just make the idler arm free to rotate and dial in more caster so it corrects when you are hooning, but the steering is still light in carparks?
Ever driven a car with a lot of caster ? "Light" doesn't come to mind when describing it, quite the opposite.
Nissan designed and tested these cars with that type of idler arm, and it worked perfectly well, providing a little bit of assistance for the steering to self-centre. It shouldn't wear out other components, and should last perfectly well for many years if in good condition. I've owned my 1600 (with the same type of idler) for over 15 years and the factory idler is still fine.
Have a look and you'll find that the lower control arms are probably the same, they are on many older Datsun's I've played with