The motor does look noticeably crooked...right rear too far to the right? If you straighten that up, the exhaust manifold will be even more of a problem. I'd definitely investigate the condition of the current mounts (and trans mount) and look into another driver's side exhaust manifold.

Did E bodies ever come w/ a log style manifold on a 383? A 383 in a grand coupe or something would have been the only possible use of a log type manifold on an E body, but I don't recall ever seeing one. Did they all get HP manifolds?