I have it solved. Took some effort, but I think this is accurate enough:
Now for details:
Nastase: pretty clean solution. 100% accuracy regarding his points and average.
Newcombe: If the 17th tournament is Johannesburg-2, it should be the only case with a 10K official tournament during the year, which might mean he received 4p for it, instead of 6, making it 141.
Smith: a real surprise to me. He's the only one not following the rules it seems. Out of all the players, his total is about 20 points above the official. Could be the biggest error, or could be something like some WCT events were not actually 50K, despite the prize money. Still, only 12.5% error here.
Connors: +1p deviation from official. That's 99.1% accuracy.
Okker: 100% accuracy.
Rosewall: +0.5p deviation from official. That's 99.5% accuracy.
Orantes: 100% accuracy.
Laver: -0.5p deviation from official. That's 99.5% accuracy.
Kodes: -0.5p deviation from official. 99.5% accuracy.
Ashe: 100% accuracy.
Gorman: This could be an ATP error. The deciding factor is Nottingham, tournament which, due to a draw of minor difficulty may have counted as 25K. Connors got the win, and it helped his 126p total. Gorman would have been at 105p if this were 50K. Seems like whoever calculated the totals (obviously without using a computer), used 25K for Connors and 50K for Gorman. I'm gonna call this as 96% accurate.
Emerson: +0.5 deviation. 99.2% accurate
Riessen: +0.5 deviation. 99.3% accurate
Pilic: 100% points accuracy. ATP errors. Again, like Gorman, ATP counted Rome WCT of 1972 despite it being a WCT Finals type tournament, which should not have counted. The average makes Pilic jump in front of Gorman in terms of rankings.
Panatta: 100% accuracy.