There is a hatch on the top arm of the National Star, not sure if it gave camera access or not.
https://www.worldwarphotos.info/wp-content/gallery/usa/aircrafts/p-51/F-6C_599_118th_TRS_23rd_FG_The_First_Black_Lightning_Chengkung_9-44.jpg
The BuNo is, US Navy and US Marine Corps BuNos--Third Series (135774 to 140052)
138948 (MSN 10809) VAH-? 'GM-4' noted deployed aboard USS Ranger (CVA-61), 1957-58 (photo) (VAH-9 as GM-11) lost Jul 26, 1960 in accident while operating from USS Saratoga CV-60. Night carrier landing, collision...
A floor mounted sight with reflector glass.
https://www.britmodeller.com/forums/index.php?/topic/235011080-airfix-p-40b-tomahawk-148th-its-arrived/page/5/
While a crew of 10 may have trained together and flew to England together they didn't necessarily complete all of their missions together due to sickness, small injury or leave. Individual crew members could/would be swapped out for different reasons on various missions.
Does the cylinder have three intake/exhaust ports and spark plug or plugs on the side?
R-1820
https://live.staticflickr.com/3290/3000214851_86eb099836_b.jpg
https://live.staticflickr.com/3003/3001055776_f876a0da70_b.jpg
The cylinder is marked Tondelayo 43-37516 which would make the engine a Wright R-1820. What is odd is the cylinder head attach bolt pattern doesn't match the R-1820.
https://www.americanairmuseum.com/archive/aircraft/43-37516
http://www.joebaugher.com/usaf_serials/1943_2.html
37516 (MSN...