Allow me to tell you there is no need to hit anything hard with an Allison 13 speed..
This is the Dill Pickle. Built from new components in the 70s with covert assist by GM Engineering.
Rebuilt from stored in 2015. The Detroit in front is equipped with factory Jake..
I was minorly involved in both projects.
If your Allison has been stored I strongly recommend rebuild, particularly the air side.
The biggest problems you face are driveline, front tranny mount and driveshafts. PLEASE install sufficient shaft catchers before testing to insure the engine doesn't stop in inverted position. Toys flip very quick when the driveshaft engages pavement and are a pure beach to sit back on the tires.
Original builder loved shifting and insisted on hitting every gear both up & down. She's won every slow race she enters, and the driver can easily walk circles around the truck in motion. Her weakness is axles & drive shafts.
It took 15 years to find the Pickle after she disappeared into the estate of the builder and 2 more to bring her back to life. She was sitting behind a barn half a mile from where she was built. The Pickle will live on in the hands of a man who loves her and cares for her.