That's pretty crazy, considering the Connors serve, the surface etc. Makes Vilas' win over JC the next year seem even bigger. Do you have complete stats on the '76 match?
According to this NY times article, the only break point that Connors faced all match, was in the 8th game in the opening set, with him saving it. He was only taken to deuce in 2 out of his 12 service games that day.
They recorded the following stats from the match:
1st serve % - Connors 93%-86% Vilas
Winners - Connors 31-19 Vilas
Unforced errors: Connors 27-33 Vilas
Forced errors: Connors 11-20 Vilas
I've only seen incomplete coverage of the match. The strategy mapped out by Segura and described in that article, hitting deep, moving Vilas out wide with powerful, angled cross court shots and then attacking short returns, looked to work to perfection. The depth of his groundstrokes, and his ability to take the ball early and on the rise really stood out.
I know that Connors faced 3 break points during his demolition of Rosewall in the 1974 final. He faced 0 vs. Borg in the 1978 final, but like Newcombe and Trabert I count that match as an effective walkover. Facing just 1 break point vs. an elite opponent in a big match on har-tru, without a booming serve as you said, was incredible.
There was talk immediately after that SF win, about whether it was the best performance of Connors' career at that point. It had to be up there, given the opponent and surface etc., alongside his destructions of Rosewall in the 1974 US Open final and Tanner in their 1975 Wimbledon SF (better than his performance vs. Rosewall in the 1974 Wimbledon final IMO).
Ashe in the TV studio / commentary booth, couldn't really hide the fact that he really wanted Borg to beat Connors in the final. Trabert predicted that Connors would win. I saw a clip of Connors' press conference after that SF, when he criticised the heavy focus on his inability to win a major in 1975; 'You bring up 75 so much, why don't you bring up 74 a little bit. There's only one guy better than me in 74 and he made me (pointing upwards)'.