Quite surprisingly perhaps, the 64 overs by Jack Leach (38-5-119-0) and Dom Bess (26-2-76-0) in the first innings of the second Test in Galle comes in only third on that particular list. When Sri Lanka ran up 756 for 5 in Colombo in 2006 - the match in which Kumar Sangakkara and Mahela Jayawardene shared a Test-record partnership of 624 - South Africa's spinners sent down 74 fruitless overs, most of them by slow left-armer Nicky Boje (65-5-221-0). And when Sri Lanka made 326 for 5 to beat Zimbabwe in Colombo in 1997-98, the visiting spinners - Paul Strang, Andy Whittall and Murray Goodwin - delivered 67.5 overs without taking a wicket.
You're right that both Jimmy Anderson and Dilruwan Perera had celebrated their 38th birthdays before the recent second Test in Galle. It was the first Test match since May 2017 to feature two players over 38: playing what for both of them was their final Test, for Pakistan against West Indies in Dominica, Misbah-ul-Haq was 42 and Younis Khan 39 (Misbah was a fortnight short of his 43rd birthday).
Those five slip catches by Lahiru Thirimanne in England's first innings of the second Test in Galle equalled the Test record. This was the 13th such instance, but Thirimanne was the first to do it for Sri Lanka, and the first to take them all off the same bowler (Lasith Embuldeniya).
In that match at The Oval in 2006 - which Pakistan forfeited after being accused of ball-tampering - Mohammad Hafeez made 95 and Imran Farhat 91 in their first innings of 504. That was the third instance of both openers being dismissed in the nineties in a Test, and there has been one more since.
The first part of this question is remarkably specific! I wondered if it was to see whether Garry Sobers, who played 93 Tests in all, was top of the list - but actually his 8032 runs places him fifth, admittedly not far behind the others. Top after 93 matches is Kumar Sangakkara, who had 8244 runs at that point of his career. Also ahead of Sobers are Matthew Hayden (8139 runs), Younis Khan (8078) and Virender Sehwag (8054). On recent form, Steve Smith looks likely to smash this record: he currently has 7540 runs from 77 matches.
Steven Lynch is the editor of the updated edition of Wisden on the Ashes