Consider, 5'10" Roy Jones beat John Ruiz weighing 196lb Could the larger framed, 6'2" Dawson beat Povetkin?
I wouldn't be shocked either way. Povetkin plods so Dawson would need his legs and to be more motivated than ever before. Dawson isn't nearly as good as Jones was. Povetkin may be just as good (I use that word lightly) as Ruiz was.
Povetkin/Dawson + 26 ft. ring = Povetkin gettiing his ears effectively boxed off for 12 rds. Too slow, too fat, no gas tank whatsoever. He wouldn't land meaningful shots on Dawson with any consistency. Povetkin would get potshotted to death en route to a descisive UD loss. Dawson would beat Vitali as well.
Prime Roy Jones would have dominated Chad Dawson. I think Roy Jones would have beat Povetkin but I don't think Dawson would.