doesn't it depend on your wheel / tyre combination, when they start to contact the inner wing?

cutting another notch sounds like a good idea, or does a rack from non-cosworth give more lock (due to smaller diameter / narrower wheels)? otherwise you could look into changing the effective leverage of the rack by shortening the distance from wheel centre to rod end mounting point somehow.

keep us updated with what you, i find it interesting trying new things like that