It's hard to tell if the metal area's around the numbers are raised or lowered. Could it be just a deep stamp that swelled the metal around the number/letters so it looks like it's filled in?
Font style looks right to me.
You didn't indicate gauge. But would it be worth it to go to this much work to fake a matching barrel for a run of the mill 20/16/12 field grade? Not sure. A 410...absolutely (as shown in our last LC Smith Journal)