Convert from fotmal [lead] to kwan [Japan]

Unit Definition (fotmal [lead])
The fotmal is a traditional English unit of weight for lead. In medieval England the fotmal was equal to 70 "mercantile" pounds, which is equivalent to 72 avoirdupois pounds.

Unit Definition (kwan [Japan])
The kwan is a traditional Japanese unit of weight equal to 6.25 kin, which is about 8.27 pounds or 3.75 kilograms.