More than just that if he wants to use a factory 6.4/392. Nothing pre-2009 can run a VVT engine unless the tone wheel is swapped and the phaser locked, which negates the advantage of having a VVT engine. The accessory drive would be totally different, a different transmission would be required.This is not for the inexperienced. Computer is completely wrong it’s missing two cylinders of control. So that would be your first hurdle wiring in engine bay and fuse Box all has to be changed. Only other option is a full standalone and then you won’t have any dash unless you piggyback sensors to the hemi just won’t have rpm on the dash.