There is a formula for Hill bows in terms of the riser length, 14 inches;, the taper in plan and profile (that I will have to look up); and their overall length (match the last number of DL to OAL, so 28" = 68". It's true they are "just bows", but they were also made just so.
They aren't conventional backed bamboo bows as in say the Torges book or video (though you can use those techniques and the basic layout to make a Hill type bow of that type, or an ILF carbon syntactic foam one, if you wanted to).
The Hill bamboos were made out of relatively large culms of the "special bamboo" he sourced. The pith was sanded out, and the backing had the nodes intact, but subsequent layers were ground in a C cross section, to make the greatest use of the power fibers in the bamboo, and allow the parts to nest together.
I don't actually think this is the best method to make a Hill style bamboo bow, It isn't the method that those cultures that made the best bamboo bows used. Preserving the most power fiber is a bit like making an all fiberglass bow with no lightweight core.
There is a lot more to all this, the main issue being once you have arrived at the basics, where do you go from there. It depends on your theory about Hill bows. What were they really designed to do. Or alternatively where do you want to take them, like say Adcock's riff on an ACS Hill bow. It's up to you how you get there and what you have when you arrive. I sense in the OP's opening post an emotional connection, but one needs to translate that into something one can build.