Overdrive Transmission for 630 HP motor
Anyone considering a modern gearbox like the NAG1 or 8hp70 should keep in mind what allows them to live behind a hellcat, or even a regular 5.7.
Torque management.
It's been used since at least the 42TE in the 90s to reduce engine power on a shift and dramatically improve transmission life. If you're not running a hemi with a factory AT computer or an aftermarket ECU that has the ability to trigger a timing retard from an external input, you'll need to run a timing retard box.