Since I have first-hand knowledge of flying both the MiG-21 and F-7M, as well as lot of time in the various models of the F-4, I would like to add a couple of comments. The MiG-21/F-7M was relatively simple aircraft that were easy to fly. The biggest issue with the MiG-21 is its lack of on-board fuel. If an F-4 and MiG-21 were equally distant from their respective basses, the F-4 could simply hold off the MiG until it ran out of fuel. The other issue of course was the lack of a real radar in the MiG-21.
Fighter pilots never, ever want to allow themselves to get low and slow...that is a death sentence. As one gains experience one learns to stay as fast and use the vertical. I would also like to note that the MiG-21 had a very high induced drag with its delta wing and so it slowed down in a hard turning fight. The MiG was then slow to accelerate out of that condition. In an F-4 you could in fact turn with a MiG-21 below 250 kts by using approach flaps (1/2 flaps). In that condition you could actually turn in front of the MiG-21 if you were above him since he could not bring his nose up to track you. This was not on the approved list of F-4 maneuvers but was effective. And here I am talking about the MiG-21Fishbed C/E and the really nice and light F-7M.
Another item to consider, since crew training has been raised, is that during my combat tour in 1971-72 at least on quarter of the F-4 pilots in my squadron had come from non-fighter aircraft just prior to their tour. This was because of the USAF policy of a single one year tour and then rotation. In addition, the USAF at that time said that any pilot having gone through pilot training could fly any aircraft. That of course is true; they could fly the aircraft but not necessarily proficiently perform the mission. It took more than a three month “conversion course” for pilot to become functioning fighter pilot rather than the pilot of a fighter.
During the Vietnam war had the Vietnamese had the F-4 and the US had MiG-21 I believe the result would have been interesting. The Vietnamese would not have been able to get many aircraft in the air and the US would not have been able to get many aircraft to the combat area because of range issues. Plus the number of booms dropped by the US would have been drastically reduced.
Lonewolf_50 - It's nearly 50 years later and the BVR RoE has been used ... how often?
During Desert Storm the RoE required two separate forms of on-board indetification, or a confirmation from AWACS. At that time the F-15 was the only aircraft that had two on-board systems capable of performing ID and were allowed to use those systems for BVR shots.