I knew the Hemi was great but..........

I've seen a couple of chassis dyno's on claimed "stock" 426's and they were in the 380 rwhp range...the rated 425 might be a bit low...maybe more like 450-460 but probably not much more than that. The factory rated 425HP was at 5000RPM and if taken higher the HP did continue to climb. Right off the showroom a 440-6 turned in better times...though probably due to traction issues on the Hemi's part, but all in all the Hemi isn't that much more powerful than the 440-6.

Here's a comparison between a '99 Viper and '67 Hemi Belvedere on the dyno...

http://www.moparmusclemagazine.com/roadtests/37426/index.html

It's an interesting comparision but from the numbers I think the Hemi might be a lil tired.