He survived being set on fire and chucked into the Grand Canyon , plus being Hanged in Van Buren. Chances are he's still alive. And I expect him to look like Darkman. Covered in bandages, and what flesh you can see is horribly burned.
Personality wise, going by from what was going to be in Van Buren, I expect him to be an apsolute psychopath. He was a horrific, murdering rapist in Van Buren, and having him as anything less would be kinda' lame IMO.
He may not be deformed at all -- he was covered in pitch, set aflame and then thrown into the canyon. There's a river down there -- if he hit the water he may have needed little more than a few stims, some sleep and a lot of Abraxo to get back in shape. 'Burned man' doesn't necessarily mean scarred; it could just be referring to his being set on fire.
It's important to note, though, that the Grand canyon is very wide and the Colorado rarely comes close to the rim -- chances are, unless they used a catapult, he'd have died from hitting the cliff faces on the way down.