I dont think it's that large. I spent 8 years working in a 100 foot long building so its certainly not that. It looks less than 30 to be honest. Remember the staff itself is less than 6 feet long and it appears to be more of a rectangular or oval shaped room.
The staff is 7 feet tall, if that helps at all. It'll be hard to judge the length of the room but it may help with the height. Once you have the relative height you can go from there.
Also, calling it "Indiana Jones and the Raiders of the Lost Ark" is blasphemy. It is and always will be just Raiders of the Lost Ark.