I think the grey area is continually growing on this issue.
Many will say a stock 727 is nearly indestructable.

My buddy ran a 388" small block in an A body. Weighed around 3500 pounds with driver.
The cars best et was in the mid 11's at sea level.

Running low 12's at another track, it blew wide open. Lucky not to lose a limb. 727 with stock 12 pin sprag, and a non low band apply VB.

My own car wieghs closer to 3800. Running about 1/10 slower than the previously mentioned A body. Same trans, 727 with nlba.

When his blew open, I decided I would go with a low band apply valve body in my car to help avoid the same issue.

When I went to install it, I found chunks of 1 way springs(from the sprague) in the pan

Pulled it apart. Debris had chewed up the output shaft so bad, I had to replace it. and best of all, there were only 2 of the 12 springs left holding it together. I was 1 hard hit away from blowing mine all over the place too

In anycase, now I have the billet drum, 16 pin bolt in one way, heavy bands and clutches, and low band apply valve body.

I sleep better now.