Here's the dirty little secret, MHz. Up until the 1800s, measurements were wildly variable. A cubit or a yard or a foot or a furlong meant little to nothing. Heck, in the middle ages, in most places a foot was the length of the king's foot, and a yard was the distance from the king's thumb to his nose with his arm stretched out in front of him. If you take into account growth and changeover in the office of king, you can see how variable these measurements were. The main reason Napoleon adopted the metric system is that it was precise and non-variable.What would be the Greek equivelent as the NT was in Greek originally? I doubt it was the cubit. 1600 is the number for the river of blood that is from the 200M horsemen and their riders. Using an English knight that would make the river about 80 ft wide using the blood volume of a draft horse and a linebacker sized guy. I'm not sure there is anything deeper than playing with numbers that would be above the level of a fisherman on OT Jerusalem. How long was a 'golden reed' (Re:21)if you want something more mystical than cubit.
This is one of the pitfalls of imposing 20th and 21st century mindsets on old things. Notions of time and space have changed. Here's another one. You know many of the clocks from the mid-1800s and earlier only have an hour hand? That's because you could tell the time to the nearest 15 minutes just from the hour hand, and nobody expected anybody to be any more precise than that.