I'd personally go with Vietnam for a few reasons that basically come down to more modern technology and the ability to have some spooky encounters in the dark, misty jungle - and I don't mean supernatural in that sense but I'm thinking of the PsyWar Op "Wandering Soul"
http://www.psywarrior.com/wanderingsoul.html
There was a location in the Ia Drang/Chu Pong area called by the Vietnamese, the Forest of Screaming Souls. It's mentioned in “The Sorrow of War” by Bao Ninh, there were many North Vietnamese/Viet Cong troops killed in the forest and it was believed that because their bodies had not been properly buried, their souls haunted the jungle. The book is a must read if you want to see the war from the other side. I think you can get the book on Google Play and from Amazon for Kindle and so on, there's a review of the book here
http://www.independent.ie/entertainm...-26327792.html
Then there's the story of the strange radio transmission believed to have been from a French GCMA unit (mobile commando forces) hiding out in Vietnam that was received by US forces when they were fighting in Vietnam... about 10 years after the French had supposedly left.
There used to be a page about it at
http://www.alliedcoldwarvets.com/GCMA.html but the domain has lapsed.
This website has some information from the dead website,
http://freerangeinternational.com/blog/?p=2291
You’ll have to go down to a comment by
Cannoneer No. 4 dated November 4th, 2009 at 19:42 It’s about two thirds down from the top of the page and the text is in italics.
Here's a list of equipment used in the Vietnam War that includes infantry weapons, vehicles and aircraft: -
https://en.wikipedia.org/wiki/Weapon...he_Vietnam_War
Another MASSIVE benefit you have if you set the game in Vietnam, is that you have people on this forum who had relatives serving in that war but better yet, you have veterans of that war on this forum as well.