Here are shadow studies for two of the Tramps photos. I get similar results of 2:15-2:25 pm for the timing. It would be great, and appreciated, if anyone interested and in Dealey Plaza on a sunny day close to November 22 would take photos of the pergola at intervals around 2:00-2:20 for comparison with the simulations. My attempts to use the Houston street street light shadow are not working well. Partially, I think there is some leaning of that tall pole that so far I've not modeled correctly.
Tramps1
In the upper left corner we see most of the north pergola. We are concerned with the forward vertical column just to the right of the Thornton sign and the next column to the right (east). The western column is totally in shadow, while the eastern column's face is fully sunlit. The closeup animation below runs from 1-3pm. There is a narrow range of 2:15-2:25pm that is consistent with the tramp photo.
(having a problem getting a photo loaded - will try tomorrow)
At left center the north reflection pool's north wall shows a number of cutouts. We see the shadow line running diagonally almost, but not quite, touching the cutout's bottom. A closeup animation of the cutout shadow runs from 1-3pm. I've re-positioned the virtual camera somewhat from what I used for the previous collage.This analysis is more subjective than the pergola shadows above, but still is consistent with a 2:15 or little later imo.