Jay, I work for a gear company and if I had to guess, the parts were probably made from a carburizing grade of steel, most common today would be SAE 8620, (a Cr, Mo, Ni steel). I'm pretty sure that even back then it would be fairly common to use 8620. They may also have used basic carbon steel grades like 1018 and 1020. Your blacksmith buddy is probably looking for some high carbon steel, like SAE 1095- or -some kick butt 52100 bearing steel. You probably don't have that.
