It appears it a similar idea caught the interest of Steve Grainger who took a classic 7-limit Pentatonic and extended it likewise up and down. This he mailed to me.
I made a mistake right off and assumed it was not a “constant structure”, that is a scale that where each occurrence of a ratio is always subtended by the same number of steps. It is a quality that gives a good melodic flow that otherwise only has harmonic relationships holding it together. Having both is worthwhile to pursue.
But I moved ahead and found 2 solutions right off for 14 tone scales. It is an unusual number to have as a scale and I seem to have come up with quite a few over the years. I am not sure why. These are illustrated and one could pick out of either set of alternatives depending on what one might like.
There is an important feature here though of Grainger’s 9-tone scale that as far as I know has been overlooked. It appears that there is a whole family of pentatonic based on 3 fifths plus 2 notes in between the fourths that will all produce 9 tone constant structures. These tones have to be larger than a 9/8 but smaller than a 32/27, most of your smaller minor thirds.
This scale would have been of interest to Rod Poole and note sure if La Monte Young has toyed with the idea, since it develops in the direction of 3 and 7s. It is in that territory
