Ben ran the 6.41 indoors in 1987 after having a perfect- and legitimate start called back- which would have given him around 6.38- exactly what he split in Rome’s 9.83. this is further confirmed by his indoor 5.55 50m WR, which is very close to the Rome 5.53 split.
He was running much faster in Sindelfingen indoors 1988, when he pulled before the 30m mark. He stopped completely and hopped across the line in 6.50, allowing Desai to close up from 2 meters down to a 6.51. No doubt it would have been a match for the 6.33 he split in Korea’s 9.79. this is confirmed by Ben’s 50y indoor WR of 5.15 around 10 days before- almost exactly on pace for 6.33.
This would be expected in a short-to-long preparation, where the required 60m will be in place first.
6.33 is out of this world (Sindelfingen-potentially). That practically equates to a hand timed 6 flat. That’s almost hard to imagine. Do people take splits of 60m races? If so where can thy be found? It seems that the top end speed in this kind of race, running all out for 60 m, would equal or exceed those achieved in Zurich, Seoul, Edmonton etc.
Perhaps, however, the smoother acceleration of the 100m allows for higher top speeds to be achieved.
There are splits from Rome of various men and women in CFTS and from Seoul in Speed Trap, available on this site in E-book format. Also the IAAF should have splits and there are splits on the site in the archives