Pretty much concur with @Grumpy Gnome here:
There's a few things worth discussing.
1. I don't believe the USMC has ever had a sizeable presence in Europe. To the best of my knowledge there's always been a headquarters and they periodically send MEUs to Norway to freeze their bits off in training rotations.
I believe it that Cold War went hot, that was their thing. Reinforcing Norway. Bit of a side theater. I wonder what Soviet/Warsaw Pact forces were pointing that way?
2. There's two main things/indicators on the minis that set the right limit of use. The M16A1s and the PASGT helmets. The triangle handguards of the A1 versus the round and ribbed handguards of the A2 is pretty distinctive. The old steel pots and the PASGTs can not be mistaken for each other.
The USMC adopted the M16A2 in 1983 and the Army in 1986. Bear in mind adopted, in widespread use, and completely replaced are all very different things.
For the helmet:
I entered the Army in 94 and saw neither hide nor hair of the old steel helmets. The PASGTs are often referred to as "Fritz" helmets in publications but I've never heard anyone use the term in real life. Kevlar, K-Pot, or helmet would be the most common names. Brain bucket or Dome of Obedience some times in jest. Also, if you're a young Private and your Team Leader asks if you "Want to hear what two turtles f*cking sound like"? Watch out. He's about to whack your helmeted head with his helmet which is uncomfortable at best.
3. Use of these minis to represent Army troops. I'm definitely a rivet counter but you can get away with it. The body armor is wrong but it's not terrible. The webbing and uniform is definitely close enough. The weirdest thing is the minis wearing the armor over the webbing suspenders. Was that the done thing in Vietnam? Suspenders over the armor for the Cold War Army of the 80s.
4. I don't think any Vietnam era vehicles have made it to today. You used to see deuce and a half trucks knocking around here and there in the 90s. The last of the Army Hueys were still supporting US Army Ranger School at Dahlonega in 2007 but I'm pretty sure they are gone. The ASV more or less is an updated Commando but they were all new builds and they are being retired/are retired as we speak.
5. Probably the paint job is most important. We need to pin down the change over from pickle suit to woodlands camflage uniforms.