I've been checking a little and actually, this scenario would have enormous possibilities in terms of multiple Unique Units. I think this could generate some very interesting gameplay.
Here's a list of the most important units I found. I'll update it from time to time with links of existing units that could be used etc.
US
UH-1 Huey, troop transport helicopter
A
AH-1 Cobra, attack chopper
A !,
(B)
B52, bomber
A !
(Napalm bomber)
A
F-4 Phantom, fighter-bomber
A !
F100 Super Sabre, fighter-bomber
A !
M48 Patton, tank
A !
M113, APC
A !
M101, 105mm towed howitzer
A
M107, howizer (tank)
A
M60, heavy machinegun
A
Marine
A
Green Beret / Special Ops
A,
B
M41, light tank (vietnamese, american-made)
A,
B,
Vietnamese Infantry (use the standard infantry ?)
NVA
MiG-21, fighter
A !
T34 & T54/T55, tanks (russian-made)
A,
B,
C,
D,
E
PT-76, tank (chinese-made)
A
DP7.62, light machinegun
K-63, APC (chinese-made)
A
BTR , APC (Russian-made)
A,
B
SA7, shoulder-fired SAM
A
ZSU-57-2, armoured flak (russian-made)
A
Chicom 63, light 60mm mortar (chinese-made)
A
the junk, transport
A,
B
NVA infantry
A !
Vietcong
A !
Khmer Rouge
use the standard guerilla