Seriously, all of those stories sound like they were exaggerated. He's probably a bad guy, but people are prone to legendbuilding... especially with criminality.
It is probably a mix of truth and fable.
The prison raping I definitely believe, there is enough easily identifiable info available on it.
The weightlifting numbers are being fudged, or are unofficial, and what you would've seen is half squats, bounce benches, etc.... Prison Powerlifting was pretty well covered from the 70's - onward, if he was putting up to close to a #2000 total, he'd of had at least some legitimate press for it like other prison lifters like Greg "Beetle" Lowe, Don Blue, etc.... Also any lifting he was doing was probably long in the past, as they would've pulled those privileges quick over his misdeeds in prison.
Also, while his story is an interesting one, there was not a trace of noble savage in this guy. Before he died in 2013, there was a push to charge him with other crimes. Most of the ones they were able tie him to were bottom of the barrel even in criminal culture. For example there was a simple mugging that turned into a murder, and a few rapes and murders of young mothers. This guy was just a real piece of shit.