Frank
I have had another look at your rear suspension and believe the bump steer problem is still there. I know you have changed the rear part but still feel that the trouble persists.
It is fundamental to the 1960s design of the GT 40s suspension, which used a lower, reversed, “A” arm.
To eliminate bump steer with this set up it is necessary to position the chassis mounting point of the lower radius rod much further inboard than that used on the KVA. Other Replica manufacturers have done this to some extent but it is a major design problem on the C type KVA chassis. In my experience, if left unmodified, KVAs location of the lower mounting point would make the rear of the car extremely nervous, even dangerous, to drive.
As you are aware there have been various solutions suggested to this in other posts such as adjustment of rear caster angle, modifying the anti squat angle etc. Personally I chose to convert my rear suspension to a twin parallel lower link set up which eliminates any possibility of bump steer. Looking at the modifications you have done to the rear of your chassis this would seem to be a relatively simple solution for you as well and one that I would recommend.
Best wishes
Tom