i dont know about the mount brackets about tourque handling.... if the big block mounts mount to them you should be high.... if the bolting seems a little weak, then you could either drill out and put larger bolts in or do a little welding..... if the torque is a big issue it'd be more likely that it'd be that the torque is too much for the factory rearend or also the unibody itself.... which in the case you gotta add shock tower braces, weld the shock towers, use a larger diameter sway bar and that such