727 sprag

Definitely. I had this trans I wanted to convert from shorty, build and test it while I break in the 512 I'm finishing up. I will throw in my fully built with the trans-brake in later when I get the car ready to handle it.
You know the trans brake puts a huge amount of stress into the driveline when it releases the engine torque all at once, right? I hope you put all the very best components into your trans during the build.