wow- that is a lot of photos
but better more than not enough
first - have the barrels inspected by a qualified double gunsmith- most 'smiths are not
and have the head of the stock inspected - looks like it might be loose or have a splitting issue
its a well worn D/3 grade- if the inspection gives it a clean bill of health - get some RST 2 1/2 shells and shoot it
as for restoration - just fix what needs to be done to make it a safe shooter and enjoy-