I know average is much different than top speed (Bolt’s top speed was 27.78, still the fastest a human has ever been clocked), but it’s a nice indicator of just how fast Richardson was moving.
Here’s info on a guy I found more in Richardson’s range:
"Marcellus Moore in the winter of 2017-18 ran an average best 10m fly time of 0.98 (22.8 mph) and his best time was 0.93 (24.1 mph). In the winter of 2018-19, Marcellus ran an average best daily time in the 10m fly of 0.95 (23.6 mph). His best time was, again, 0.93 (24.1 mph).
Since Marcellus was capable of running 24.1 mph (10.77 m/sec), he was capable of running a 9.28 100m fly.
How about Marcellus in the open 100 meters? Well, if you add one second to 9.28, Marcellus would have a ceiling in the 100m of 10.28. He ran 10.31 for the IHSA All-Time Record. That’s 99.7% efficiency."
Marcellus Moore is currently a sprinter at the University of Texas and according to their website: “Became the fastest sprinter in UT history finishing second in the final to Trayvon Bromell with a time of 6.56, finished the 200 in 20.78 to move to No. 10 on the all-time performance list.”
So overall I think we’re talking really elite speed for Richardson.
