Awesome report. It looks quite big from the pictures
The tunnel down from Main West is about 12ft wide, the main vent duct is about 25ft wide and 15ft high, the fans are about 8-12ft diameter. There was a battery room about the size of a single garage which I didn't get a piccy of which had shelves of 10-gallon size glass batteries for the emergency lights. At one point a group I was involved with were looking at doing a sponsored walk and it was suggested doing it down the mine. I worked out that covering all the passages you could walk about 10 miles!
So, yes it is a bit big!