If you were building one I would recommend an all in one cable that hooks straight from a USB port to any model t particularly the model 100 with no adapters necessary.
Also it should be full null rather than defeating flow control as the old complink cable did in order to support programs like HTERM which rely on flow control. And ftdi is the only way to go on Windows. Maybe a very small pcb that can be built into a thin hood shell with a surface mounted ftdi chip and max232? All that said you could accomplish mostly the same thing by simply aggregating the proper OTS parts and software and offering it for sale as a package with documentation. That way it takes out all the research and guesswork and that's the real trouble. -- John.