RE: 7.0 Hemi?
Not true. There is a 6.9 that has been developed for SRT and is in the product plan for Challenger, but I don't know if it has been approved. And as far as I know, it's just a Hemi, not some DOHC thing.
Besides, they won't need DOHC to beat the LS7. LS7 makes 505 hp. The 6.4 that is going in the SRT Challenger should beat that without a problem.