I really like what you did there Udall to extrapolate the dims. based on the picture but I have to agree that the grips are slightly larger than the numbers you came up with, but not by much, and probably the best thing you came up with is that you got the proportions right so pretty much any dimensions can be based on those proportions.
I have to think that because I want some grips like this on my bikes I can't be the only one, but I'm not interested in turning this into one of those threads like "Hey guys I want to start producing this widget how many people want to buy some from me?" It's a tired story and I wish I had a nickel for every time I've seen early enthusiasm fizzle out on I don't know how many forums.
The first thing I want to do is see how easily we can reproduce some of these grips and just how efficiently we can do it, then we'll go from there.
Another question, what do you think these grips would have been made from? Maple? Ash? Hickory?