IMO a scale like this would be wildly inaccurate because you can't account for the variable of setting. In my experiences with psychedelics, setting is almost as important as having quality drugs. I guess you could just base it off how fast your body breaks down each chemical, but even that can vary widely due to differences in metabolism and body weight. In my experiences with combining MDMx with LSD/psilocybin I have just gone by "feel" and have had some wonderful experiences. I realize that this method could be dangerous for someone who doesn't have extensive experience with these powerful drugs. It's also extremely important to know the strength/quality of the substances you plan to ingest prior to combining them in your body.
Thanks for the pointer -- actually I was just trying to add a question to my post that I hadnt thought to ask. I felt like it would be better to pose it in a new post rather than an edit since it was a new idea.