I think the OP is asking about famous historical professionals, i.e. those from before the 20th century.
The thing is, from the 16th until the late 19th century they mostly played
Sunjang Baduk in Korea, which has significantly different rules.
The Korean Baduk Association has
an article which mentions about the 16th-19th centuries:
Famous strong Baduk players included Lee Deok-won who played with Li Rusong, the general of the reinforcing Chinese army, Yun Hong-yim, Yu Chang-hong, the artist Choi Buk, Sin Gyeong, Whang-O and others.
and also about the late 19th century, when modern baduk rules were being introduced:
Kim Man-su, Bek Nam-gyu and Noh Sa-cho were recognized as Kuksu, but in the Sunjang Baduk succession.
As to their strength, let me quote a GoGoD article about Karigane Junichi, then 2 dan professional, who visited Korea at the close of the 19th century:
There were two strong Korean players at that time. One was away on a trip. The other was Paek [Paek Nam-kyu, I assume this is the Bek Nam-gyu mentioned above. --Herman], who did challenge Karigane. 15-year-old Paek, however, was not a full-time player nor destined to be one. He was to become a member of the Privy Council (he died only in 1970). He had, nevertheless, been able to trounce all the Japanese then resident in Seoul, and so was supported by them, as defeating Karigane would save some face for them. Paek took the seat of honour and Karigane had to play first - but with White, as was the custom in Korea. They alternated between Japanese rules and Korean sunjang go. The uchikomi rule was in force, that is with handicaps adjusted after one player was four games ahead.
Karigane ploughed a straight furrow, beating Paek down to a four-stone handicap in Japanese go and a two-stone handicap in Korean go, without losing a single game. Still, it was not always straightforward for Karigane. In their last game, in a lost position, he won by three points through a swindle. Statesman-to-be Paek praised him as a genius.
