Try to find the spot where the photographer was standing.
Several of those men were North American Aviation test pilots. You might investigate along those lines. They might all be.
Roy Ferren was an engineer for North American.
http://www.flickr.com/photos/chrisk48 Thanks for the lead!
¡ Wonderful image ! Excellent your work. Congratulations and a greeting.
Mi Web. www.telefonica.net/web2/jlbarreu/
Great shot. http://s01.flagcounter.com/count/7uR/bg=FFFFFF/txt=FFFFFF/border=FFFFFF/columns=1/maxflags=1/viewers=3/labels=0/" alt="." width="1" />http://s09.flagcounter.com/count/9RU/bg=FFFFFF/txt=FFFFFF/border=FFFFFF/columns=1/maxflags=1/viewers=3/labels=0/" alt="." width="1" />http://2.s01.flagcounter.com/count/7uR/bg=FFFFFF/txt=FFFFFF/border=FFFFFF/columns=1/maxflags=1/viewers=3/" alt="." width="1" />http://s01.flagcounter.com/map/7uR/size=m/txt=FFFFFF/border=FFFFFF/pageviews=1/viewers=3/labels=0/" alt="." width="1" />
plus, the personal flight gear shows a lot of personalization, no military ranks are given, and their doesn't appear to be any military insignia visible, so I would agree with the theory that its Republic test pilots.