The 2:1 kill ratio is about right for that conflict. However, it's hardly a meaningful metric for comparing two aircraft. I'm sure most here will understand that, but just in case... ...the home team has GCI, closely based replacements, operating well inside their range and aren't facing other threats or trying to execute missions other than air-to-air. There was also a significant RoE issue. So, nice numbers, but the wrong vehicle for comparison.
You can do the sums yourself if you so chose, but in round figures the overall F4 kill ratio is around 3:1 (306:106), MiG21's is around 1:2 (240:501). Again all in different conflicts so no more or less meaningful than the earlier comparison.
And there are lots more factors involved in assessing combat effectiveness that just going up head-to-head. As we all know.