Joe,
I can think of one explanation why the jig looks like a 1/64 instead of a 1/80th and that is if the jig is made from tin, or a bismuth/tin mix. Jigs of these materials are lighter as the tin or bis/tin don't weigh as much as lead. Usually the weight is 2/3rds or less of the lead jig head.
With lead laws in different states you also have to be careful.
There's a bunch of guys who sell jig heads on this site, check in the for sale section, and call them and tell them what exactly you want and have them give you a price.