I would tear that used engine down and do a basic refresh, so you won't have any more surprises like this. All you'll need is a re-ring / bearing kit and some elbow grease. If it all measures to spec and inspects fine, you are good to go. If not, you just saved yourself another engine drop and a bunch of hassle. "Wrecked Firebird" doesn't sound like the engine had a good life.
George