I'll take Heller and Catch-22 over MASH. Heller was there, flying the nose of a 25 and while Catch-22 is best described as an exaggeration, there is a lot of truth in it, and those who've dug into the actual 340th BG have been able to connect the movie characters to real members of the unit. They really did keep upping missions on those guys. Concentrated bomb patterns were a huge deal to the people in charge. Interestingly enough Heller was used along with other members of the 340th to make some 'training for combat' films while with the 340th. There is a nice article about that, with links to the film clips of Heller in a 25 and elsewhere here:
https://unwritten-record.blogs.archives.gov/2014/09/17/the-reel-catch-22-pt-2-joseph-heller-and-training-during-combat/There is a book called "The True Story of Catch-22" by Patricia Chapman, that really digs into the story. Her dad was Group CO. She connects the dots really well. and it gives you a different perspective on the book and the movie.
Heller in the nose of a 25
Heller in his A-2 jacket. Note the patch on it that is seen on Yosarrian's jacket in the movie and elsewhere.
I'm lucky enough to have in my little collection of WW2 flight gear, the flight jacket of another bombardier from the 340th who was in the same squadron as Heller, but a bit later in the war. He flew the same nose of a 25 that Heller had done missions in previously. Needless to say that made me do some serious digging into the 340th BG