Dear WW: Imagine walking up stairs. A step per second is about right, I think. There is no advantage to doing it either much slower or much more rapidly. If you count "one thousand, two thousand, three thousand.." , the counts are pretty close to a count per second.
I think the Indians could go up a step each second, and each step could be a foot high. So two hundred pounds of ore, plus a hundred and fifty pounds of Indian, rising one foot per second is 350/550, or .63 horsepower. Hey Bean, where are you when we need you?