Did you factor in suitable amounts of time for maintenance and cleaning or is this just a rough estimate of the job?
Just a rough estimate. I figure if you put the thing on a hill you could use a chute to collect the heads and dispose of them pretty much real time. You could do sculpture. In 1398 Tamerlane built a pyramid of 90,000 human heads in front of the gates of Delhi. Do you believe that nobody has topped that since? We’re Americans, dang it, we can do it!