If you don't have access to welding or welding abilities, but can hard solder or braze, you can extend the tang the correct amt by either of those methods.
Doing dovetail joint between the two pieces instead of a plain butt joint further reinforces it and when done the whole piece is filed back to the shape you need.
Go ahead and inlet the now repaired tang d solder into the stock,,yes it will have a hard solder or braze line visible but that'll go away in the next step.
Once the tang is inletted and fitted, shaped closely to the contour of the top of the wrist, remove the breech bolt from the bbl and mark the entire tang,,front , both sides and back edge to an equal depth from the top surface. The amt needn't be more than 1/16",,less is OK.
What you are going to do is replace that evenly removed material from the top surface of the tang with one piece of thin steel and soft solder it into place. Something akin to half soleing a shoe.
That will cover the braze repair line underneath so it won't show on the finished rifle. It's thick enough to be further filed and finished if needed but should be near done which is why the tang was finished up to begin with. It can be engraved at that thickness too.
Sounds like a lot of work but it's not really hard to do. Plus it's a way of saving a cut or damaged tang for the welding challenged.
Just another way of doing things...
