A couple of reasons, the weight is one and the heads are stock on the 396 so its def just a cruiser at this point. A decent set of heads would really light her up but BB heads AFR are like 3K plus!!!! Hell I can get a entire 383 short block for that. Dont get me wromg the BBZ is awesome and has a wow factor like no other but Id rather have that gravitational pull in the pants from a 383 with less weight and a little more room in the engine bay. I have always been an auto guy as well,,,something about touch and go and just hold on.
Other than that there is no reason really. However I may just swap a 454 in the future too....who knows! Having something rare and unique is also cool.
Terry