OK, I pulled the stock off. There is no other markings under the stock, but there is 272 stamped into the inside of the stock. These are the last three numbers of the serial number.
A Marbles front sight is a good idea but there really isn't a local gunsmith to help me. It's just me and my buddies in a shop with lots of tools. Is there any way I can determine the correct front sight height by myself and order a Marbles front sight? I'm sure we can machine the dovetail and make it fit.