Dude, you are wasting a lot of time splitting hairs over the temperatures during the '88 heat wave/drought, as if 100° was some sort magical number. So what if the actual temps at first order stations were inflated by a degree or two? As you said yourself, it was the worst since '36.
As an aside, I was 30 years old in '88 and drove from Indiana (with no a/c), spending some time in Philly and D. C. during the height of the heat wave. I saw several mercury thermometers that registered 100° or more in the shade during that trip. And it wasn't a one and done, it was days upon days of mid and upper 90's. It was most extreme heat and dryness I have ever experienced and is still one for the record books, whether the thermometer read 102° or 99°.