Epps is due to portray the See No Evil, Hear No Evil star in Nina, which features Avatar's Zoe Saldana in the title role.
Pryor's widow, Jennifer Pryor, has now revealed she received a phone call from Epps before the casting was announced and she gave him the green light to take the part.
She tells TMZ.com, "That was very sweet and respectful that he called me first. I am happy that they picked him. He is a real good guy."
Jennifer also admits she would be happy for Epps to play her late husband in a film of his life, which is currently in development, as she is not impressed with rumours linking funnyman Eddie Murphy to the role.
She adds, "Having Eddie Murphy play Richard Pryor would be like having Al Jolson (white actor famed for wearing black make-up on stage) play Malcolm X... He (Pryor) would want someone authentic like himself."
Filming recently began on Nina and the movie is due for release next year (13).