The guy has been a world class actor and performer, so let's consider what level he could have gotten to as a track athlete. Of course, I am asking about when he was in his prime (well before the accident in the early 1990's), and during that era, fast Mondo tracks didn't exist, and training was a lot different... so, for argument's sake, assume he could use all the modern science / technology for training and racing.
I say 49.3 for the 400m. That's for a race, not a relay split.