Perhaps just going over the basics of driving a non-power steering car with her might help. Which just entail never trying to turn the wheel with the car fully stopped. Inching it slowly along as you turn reduces the effort tremendously. Pumping up the tire pressure slightly helps too (make sure you keep the rear slightly higher than the fronts to maintain safe understeer).

If the steering is stiff while moving you might have a dry steering box or some stiff ball joints.

The geometry of the steering linkages is not conducive to tinkering. On my 544 I tried swapping to left and right arms from the hubs because they had a very slight curve on them and I needed a little clearance for some wider wheels I had. Tried driving it once and it worked well straight ahead, but once the wheel was turned it would pull hard to lock and really scrub the two front tires against each other. I put it all back to normal and got some different wheels.