I think people get all goo goo over the 427 small block. Small block..big block...truck engine...whatever. What matters, IMHO, is the displacement, the amount of power generated per ci, and the reliability of said engine to handle upgrades/modifications.
One of the reasons that GM is getting 427ci out of a small block is because of the paper-thin distance between cylinders and the stoke. Otherwise, they'd be foreced to go to a big(ger) block. That's why the original 427's were big blocks...it was necessity as they didn't have the technology back then to make 427ci reliable in the small block. To surmise what GM could do with an additional two cylinders is purely speculation and could be as high or low as one wants to be within the physical limits.
I don't know anything about Dodge's V10, but I'm going to guess that it's cylinders walls aren't nearly as thin as the LS7. Thus, it could be surmised that the Dodge's engine isn't as 'fragile', for lack of a better word right now. What if Dodge used the same clearance between cylinders walls as the LS7? What would be it's displacement then? What would that do to the HP and Tq numbers?
I think it's somewhat silly to try and compare the two except for exactly what they are, AS they are. So the Dodge uses more displacement to get similar power as the vette. So??? I believe they use different technologies to get to that point as well (e.g., cam setups) Just as the imports can lay claim to big numbers using smaller displacement than the vette. "Oh, you need 8 cylers and 7L to get what we are getting in 4 or 6 cyls and 4L." So what? Different approaches to reach the same end result. I think beyond that, the next question is that of reliability and/or the ability to make modifications without getting beyond the threshold where the engine becomes a grenade.
What can Dodge do with their V10 if they really want to bump up the power? Does the LS7 have the same leeway? I don't know, I'm not that technical.