Problem is, nobody would want to fly for Vietnam. It would just be F-4's buzzing around looking for that one guy in the MiG. Notice how not one supportive post here is by a guy who'd fly for North Korea or Vietnam. They all imagine being in the F-86 or F-4, but who they imagine they would fly against is beyond me.
Alternatively, it would just be F-4s fighting other F-4s if done like the AH MA.
I think either would be boring as hell.