In an earlier post, I described losing reverse in my newly built 727 while running it in on jack stands! The trans builder promised that he could build an automatic shifting 727 that would hold up behind my 600 ft.lb. torque HEMI. When he stopped by to examine the pan, he declared the trans "terminal".
I talked to two builders who are recommended on this site. Both insisted on a manual valve body.
How much power have you guys been able to push through an auto shifting 727 before failure? This will be a 99% street driven car. Full weight 66' Coronet convertable.