1983 I might give to Wilander. He did have a 3-0 record against McEnroe that year, more tournament wins, fewer losses, performed better at 3 of the 4 major touraments, a better Davis Cup record. Are you including the Masters played in January 84 as part of your argument? I tend to include it in 1984 since that's when it's played even though the Masters is supposed to be the season ending event.
Also I would discount Connors from the 1977 argument. However, I agree with you splitting Connors/Borg in 1978. Most people just tend to see Borg 2 majors to Connors 1 but I would say they performed pretty evenly throughout the year.