We are getting close, I found plans for their 4' 1 gauge Camelbacks in a digitized edition of the January 1887 Railroad Gazette. There is a chance plans might be in undigitized editions. C&H had several different orders of the Mason Bogies, with the early deliveries coming in 1872 with the Calumet and 1873 with the Torch Lake (the one surviving today), 1880 and 1882 with the slightly larger Red Jacket and Raymbault, and finally the largest Bogies coming in 1887 with the Schoolcraft & St Louis. Try looking for copies of Railroad Gazette that coincide with build dates for the bogies, usually within a year or so.