The obvious answer as to why the 8 speed is in my chart of the gear multiplication. Plus, the shift speeds I believe is around 20 miliseconds.

Sound German makes the TCU that is needed. This needs an RPM and brake signal.

Yes, the bolt pattern for the new Hemi and Magnum/LA are the same so they bolt right up. However, there is some finagling for the flexplate/flywheel/converter, mainly due to the tone ring on the Magnum flexplate and the balance on the converter.