Ok Cathy, Here's where I have to play the skeptic. Logically, if he had taken a train and raced it he had to do it without anyone knowing, as he didn't work for the railroad... therefore he wouldn't have had anyone actually keeping time. He may have done it faster than anyone could remember but it wouldn't actually be a record per se.
But if he did steal a train, which is entirely possible, then I'm sure it was newsworthy and somewhere it was recorded. That should be a cool "family tradition" if it can be proved.
I'll see if I can find anything online about it.
P.S. I say it's possible because as a kid in the 60's we used to climb into the ones left unattended on the freight train tracks in Braintree, Ma. If I knew how to run one I probably would have started one up at the very least.