Interesting picture. Wished I’d found it on eBay. The first B29 is indeed “Top Secret”, 44-27302 V-72. It flew 6 “pumpkin” bomb missions from end July to 14 August 1945 with the 509th Composite Group. The Pumpkin was a high explosive bomb with characteristics and shape of the A bomb, Fat Man. Used for on the job training on Japanese targets.
The second in the row is indeed the Enola Gay.