There is a way to transplant original wood, but its tedious and might not work in this case, but it involves drilling a small enough hole to be able to thread in a blade from a jewelers' saw to cut a dovetail from the damaged area, and the whole damaged area can be slid out as a dovetail. As you dress the ends of the dovetail, it will be looser in the notch, but with shims behind it, it will also be raised up from the surface. When it is high enough to dress down and re-checker, the only foreign wood will be the shims and not the whole patch. If you're lucky, you might even be able to cut a couple slivers from the bottom of the dovetail notch for fillers to hide the shims.