The 83 mph gust at Matinecock Point was from a WeatherFlow station and was slightly elevated (45 feet or 13.7 m versus standard 10 m anemometer height). It converts to around 80 mph at standard height. The station is called Bayville by WeatherFlow, but is actually located at the northern end of Glen Cove, slightly west of Bayville.
Another elevated WeatherFlow station (71 feet or 21.6 m, on top of a lighthouse) in Eatons Neck reported a 80 mph gust, which converts to around 74 mph at standard height.
A Weather Underground station in nearby Centre Island reported a 67 mph gust.
Per the WeatherFlow stations, gusts on the immediate South Shore were a little lower than on the immediate North Shore. Highest gust I saw from WeatherFlow stations on the South Shore was 60 mph in Oak Beach near the eastern end of Jones Beach Island.
You can view the WeatherFlow data (for a limited time, as long as Hurricane Iota is still around) here: http://ds.weatherflow.com/storm/iota#40.641,-73.27,15,19