Let's see (I've been thinking a lot about a revival of Evita lately)...
On Ripley and Murney as Eva...judging by albums, I'd have to go with Murney. You must remember - Eva has to be young (she died at all of 33!). I can't really think of many others who'd really be right for the part.
Raul Esparza as Che. But you'd have to give him the movie version of "The Lady's Got Potential" to sing. That said, there's no one else who could do it right now.
Peron...no idea.
What about Philip Hernandez as Magaldi? He's got a great singing voice, and he was excellent in Les Miz (he played Javert until a few months before closing).
Totally agree with Jessica Grové as the Mistress. Then again, I agree with her as anything...but I'm biased toward lovely women.

Anyway, I must say: any revival should abandon the Hal Prince staging entirely, reconceive it from the ground up, and definitely bring out the rock sound that is present on the concept album and in the film. Ditch the rather dull "Art of the Possible" for the film's "The Lady's Got Potential." As for physical production, I have a vision involving lots of translucent scrim and a large, mobile staircase...
-Wayne