As an actress, when I get given a role, I love it when there's a load of research to be done; books to read, Wikipedia pages to comb through, films and documentaries to watch. If you're playing a person who actually exists (or existed) it can be a gift... or a curse. You don't want your performance just to be an impersonation - presumably you were cast to bring life to the character, rather than because you could be mistaken for them on the street. Perhaps the person has an accent that might alienate modern audiences due to its period peculiarities?
This is why I've been so enjoying watching The Marvellous Mrs Maisel lately. Have you seen it? It's on Amazon and it's funny, poignant, heartbreaking and uplifting. All the performances are spectacular and I love those vintage Jewish accents (it's set in late 50s New York) but I particularly love Luke Kirby as Lenny Bruce. Lenny Bruce was and is a cult icon, and he had a very particular accent. Very much of the time and the area. Kirby has clearly done a lot of research and probably worked with an excellent coach.
Check the show out, I think it's illegal not to like it.