Oh BonnieBunny, what you're undertaking is a courageous enterprise! I'm afraid nevertheless that creating a Cold War and post-Cold War scenario continuing from 1948 onward would require an entire developers' team to tackle a long list of items like expanding correspondingly the technology tree and the evolving military equipment, the possibility of revamping the ideological triangle, introducing post WWII political arrangements and peace settlements, factoring the Cold War tensions and the possibility of war anytime, even from the AI side, etc. If you're working alone, and only interested in several South American events, on a region that didn't feature prominently in this historical phase, your mod is bound to be very limited for the community of players.
What is your take on these issues?
Really, if you can surpass all these difficulties, you're going to do a really great thing. I was also thinking about how welcome would be continuing of the timeline until the end of the Cold War ,at least. That would be a true achievement. HOI 2 did have such a dlc/scenario. Unfortunately the game developers didn't follow through with HOI3. In many respects HOI3 is an unfinished project.