I'd do what SKb suggests, plug and let the wood finish do most of the cover-up job afterwards.
Matching grain and color as closely as possible of course first but with a heavily used stock w/ plenty of 'patina' to work with, a pristine final finish isn't what's called for anyway. So much the better in this case.
Same goes with the toe repair.
Restoration isn't always about making them look like they just came from the factory. Quite the opposite actually.
Another way is to overlay the entire ear of the stock.
Make the suitable repair with existing bolt or other then leave it sunken from the surface.
Take the entire surface down enough to overlay an entire new thin piece of walnut onto the ear. Glue in place. Trim and shape to fit.
Veneer is fine for the one side where the hole is entirely within the panel. That can be as thin as 1/32 in or less. The edge can be shaped into the stock existing concave form.
The other side will need a thicker piece or a 2 piece inlay. Neither is hard to do. The joint betw a two piece will fall right where it's easiest to add darker grain lines and extra patina to the final finish to hide such things.
The gun is a great project for learning some skills on. Looks like it'll make a decent shooter too.
Ejector gun,,,#1 frame,, 12ga,,,not bad at all.
The orig butt plate and grip cap are fixable too. It's some work but again that's restoration,,saving what is original.
New casting of fiberglass are of course available for fitting. But then that's what you have on the orig gun,,brand new reproduction fiberglass castings of the originals.
JMO of course.
