If you are right, it is designed to attach to an 8 mm cine camera's turret. I've had such cine cameras, the finder lenses are specific to the taking lens and are usable only as intended.
But be happy. You have an Angenieux lens, whether you can use it or not. When you feel down repeating "I have an Angenieux lens" will make you feel better.
Thinking of cine cameras, what results have you got from y'r little Bolex?
Doing research and thinking things over before buying is always a good idea.