Well, the problem is that you have been presented with a lot of evidence from his career, the concrete reality that he never indeed run a 800m time trial, plus a whole lot of knowledgeable people here agreeing that a ~1:42.5 was quite realistic for him, and yet you fail to concede that you are wrong. The problem is that you also don't counter any of the arguments you have been provided with, neither you present plausible arguments to defende your case.
Your only argument is to say "he was a 1:44 runner because that's what he ran in his career" which is as poor as an argument as claiming Jim Ryun's potential in the 1,500m and the Mile were respectively 3:33 and 3:51 because that's what he ran. It doesn't make sense.
Coe broke 1:43 twice in his career and these were the two time trial races that Ovett never had, this alone coupled with the fact he ran 1:41.73 should be enough for a reasonable person to agree that 1:42 mid (at least) is very reasonable for Ovett in a time trial race.
You have to understand that many runners have personal bests that are significantly weaker than their respective potentials, and these claims are based on reasonable arguments by reasonable people analzying their careers. This is just the concrete reality, your denial just makes you look delusional.
Be humble, look at how Ovett ran and some stats of his best races, and just admit that you were wrong, and that is fine.