It's basically what I posted on here a few weeks ago. Josiah Black and Matt Passmore are 2 actors in Saw: Legacy. Looks like Josiah Black will just be a victim, probably in the car trap, as he was only on set for a short time, around the time the car trap was shot. The other guy is his stunt double, suggesting he needs a stunt double, so I bet he dies in that trap.
Matt Passmore is still on set and has been since day one, I suspect he plays a main character.
Other than Tobin Bell, nope :/. He's also been there almost the whole time too, so I assume he'll be in a good chunk of the movie. Don't know if that's voicework or otherwise.