I think the checkering pattern isn't far off. Here is a link to an original XE that sold at auction. You can blow it up a bit and get an idea of what the forearm metal should look like engraved in the XE pattern:
http://www.icollector.com/Gough-Sign...otgun_i9966116
Doug Turnbull restored one and I think the checkering pattern is much like what was done to yours. Here's a link to that one:
http://www.turnbullmfg.com/store.asp?pid=27865