I'm a machinist not a gunsmith, but have "strong backed" a couple of similar cracks on Sterlingworths.
If you remove the lock and there is nothing else to interfere, and I don't think there is, you could dremel a small groove perpendicular to the crack on the horizontal surface, and accraglas a .060 to .080 diameter, grooved or knurled, steel or brass pin in. Cover it with a dust/acraglass mixture, replace the lock and it would be semi invisible with the lock removed. Then you just have to deal with refinishing over the visual crack on the outside.
If it were mine, that is how I would approach it.
Just a thought.
Hope this helps.
Bill
Last edited by ithaca1; 02/28/15 12:08 PM.