Years ago, in an effort to improve vacuum braking performance , I swapped out my 9” dual diaphragm brake booster to a larger 11” dual diaphragm booster . I don’t recall exactly, but think it was for a B Body car.
It fit, but doesn’t leave a lot of room for the other stuff, but no issues .
Eventful went to a HydroBoost system which I’m very happy with