A little applied engineering speculation (SWAG) :
Assuming the diameter is 580 ft (based on 600 ft height), then the circumference will be about 1822 ft.
If it has 30 cars, it will have to stop every 60 ft to load/unload.
If they exit one side & enter the other, they can probably exchange a load in 30-45 seconds.
In order to mimimize stress on the structure, they would not try to get much speed between stops. My guess is that it would take 20-30 seconds between stops.

So, we are looking at (30*30)+(30*20)=1500 seconds = 25 minutes on the fast side and (30*45)+(30*30)= 225 sec = 52.5 minutes on the slow side.