To help you a bit if you care about accuracy. (I know, it's a fictional campaign anyhow) The units still flying the A-7D were mostly ANG. But one Active-Duty hung around until '81.
The 23rd TFW (Flying Tigers) out of England AFB, La. It's actually represented with tail codes in the defaults decals.
Here are the Guard units:
114th TFG, SD ANG started in 1977
121st TFW, Oh ANG started in 1978
127th TFW, Mich ANG started in 1978
132nd TFW, Ia ANG started in 1977
185th TFG, Ia ANG started in 1976
140th TFG, Co ANG started in 1974
156th TFW, PR ANG started in 1976
162nd TFG, Az ANG started in 1978
169th TFG, SC ANG started in 1975
As a stretch, you could also use the 355th TFW, Davis-Monthan AFB. They tranferred their aircraft to the ANG in 1979.
Good luck.