I was wondering if anyone could direct me toward a source in answer to the following problem. I'm looking for a source that provides full and accurate metrological data on Spanish-American bust 8 reales from 1772 to about 1820. The mints that I'm interested in are Mexico City, Lima and Potosi.

I'm after changes in silver fineness, weights, diameters, and thicknesses over those years for each of those mints. One would think such information would be relatively easy to find, but the data is often inconsistent or unreliable, and diameters and thicknesses especially are missing altogether.