Not really helping with the question, but I am looking for the same info but for a different reason. I built a bass vi using a 30 scale bass neck, hence a 62.5mm heel width, which provides a more user friendly string spacing than the normal vi arrangement. Now I want to repeat the process with a semi acoustic or hollow body, but very few have info on string spacing except at the nut. So I guess 55mm at the 12th will mote or less equate to 62.5 or 2.5 inches at the heel?