Your picture is worth a thousand words, thanks for including it.
I think I see something that is contributing to the over-steer: Your front track-width is maxed out to the fender lips (good thing) but the backs look tucked in a bit too much. Could you please confirm and take a track width measure of the front and back (outside to outside of tires) and post it?
Could be a minor adjustment here and then the rest of what you have planned will get you where you want to be.
