I thought all the 62-72 B, 70-74 E and all A body cars had the "Anti-Dive" built in as evident by the lower position of the rearmost UCA bushing.
They do.
It just doesn't effect bump steer on the a body.
Correct.
And there's many other geometries that effect bump steer too. The Anti-Dive is not the only thing. There may be some things that cancel out others. But the net sum overall on a A-body is not bad at all.
That said. My car is lowered and I only measured to 3". Not really going to get to 3" extension/rebound on the street or roadcourse. Especially with higher spring rates. We're not Off-Roading this deal.
Now on a drag car the light front spring rates may pull the front tires nearly or completely off the ground. In that case, extension/rebound may get over 3". So the range of concern is much higher on those cars.