Gentlemen, thank you very much for your help and interest!
So Mr. Jack Walker Howard was quiet ambitious during his military service. Though is it thinkable to transfer from a fighter / recce unit to a heavy bomber unit during the war?
This article of July 19th, 1943 of Fort Worth Star-Telegram (newspaper) has a picture of a certain Lt. Jack Howard of Llano, Texas:
https://www.newspapers.com/image/636...Howard&match=1
Age, origin, etc. fits pretty well to our Jack Howard...
So, if we count on the newspapers he has been part of a fighter / recce unit that has been active in Egypt and Tunisia around September 1942 to February 1944 at latest. Roughly said the 57., 79. and maybe the 324. Fighter Group did so. I am still checking on the net....