I checked my sources. It was an article in Autoweek 15 Feb 1969 p10 that said the first Mk 3 went to Fred Hummell. It implies the second went to Karl Knapp and the third as a FB for Bruce Eglington and later for Earl Jones. So Jones' Run-Offs car looks like it was chassis 3.
Bruce might be able to remember more:
http://www.bruceeglinton.com/
Allen