6,270 lbs is a really big number and difficult to believe.
I don't know much about weightlifting records. If you Google the subject, you can find
articles that tear his claim apart. He apparently did the lift in his backyard by piling junk on a table he built, and then lifting the table. And then weighing the junk. Maybe he made an addition mistake. That article mentions a safe that weighed 1,200 lbs
less than he claimed it did. He claimed three people were witnesses, but at least one of those witnesses said they were not there that day but just heard about it later.
He was a strong man. There are plenty of official records out there of lifts he did, and he was an olympian. Nothing to be ashamed of.
But 6,270 lbs? That's 3 cars at once. No way.