I've got the info somewhere, but the statue is based on the legend, not the other way round. It was set up in the 1970s.
I've read both Chappell and Johnson and from the descriptions of people who claimed they had come across him, collected in the 1920s, he was more than one person anyway (very big, very black; small and light skinned etc.). Using the hammer with both hands appears to be a description of ambidextrosity in the earlier sources. Apparently, some of the better hammer men could do this.
The postage stamp portrait is a picture of the statue and, for anyone who wants it, an internet search on "John Henry Days" brings up the Talcott site (which is becoming increasingly more commercial and less informative).
I have a copy of the Blenkinsop broadside copied from Johnson (it's a photographic plate in his book). It scans well if anyone wants it.