As great as John Hurt was in the role I can't help but wonder what might've been had Jon Finch beem able to carry on with the film. Dude was a killer actor and looks great in costume in the photos that were taken on set.
https://avp.fandom.com/wiki/Jon_Finch#Gallery
Funnily enough there's a small possibility that Finch's voice is actually still in the movie. One very brief line while Kane is not on view: listen for the "Keep trying." https://www.youtube.com/watch?v=vFMbnJnocSk&t=128s
Sounds quite a bit more like Jon Finch than John Hurt does in the rest of the scene.
Some Jon Finch speaking parts for reference: (https://youtu.be/4JIMbdJObGM?si=KVX8OpUrYGTkr2kZ&t=20s)
(https://youtu.be/Hj6gQhpMW30?si=oRA2Nhi7LXHJb6_r)