So, after a little digression, I can report back that I have now refitted the standard steering wheel, which I can hardly see over the top of, and the steering shake or kickback is as bad as ever, so not caused by my changing to an 11" [280mm] steering wheel.
Apparently the factory are reporting that they have changed the shock absorbers on one car so far, because of this, probably Simmos, does anyone know of any other cars so affected and what the cure is? I really can't see that the geometry being out a bit can cause such a bad reaction, but, maybe it does, what do I know?