ooh, tough choice! the beechwood is a light coloured wood and fares well,if you dont want to worry about its appearance but are more concerned with practicality, its a good stock wood, but the walnut with care you can get the most amazing graining from and a finish which is quite good looking, with a walnut grip use a light oil, walnut oil works well for bringing out the finish, depends on what they have done with the woodwork before you get it though, but if youve got the choice walnut fine polished is a very good looking choice for stock,though on the down side you dont want to damage it once youve got it looking good, do examine before buying though so you dont end up with a rough looking one,(unless you want a standard service finish)shouldnt be a problem , anyway my tuppence worth there,
if its a harder to find ammunition look at availability and future supplies, or maybe even a reloading kit? depends on what you want really,
just thought of something your probably already aware of, but a lot of old rifles havent been reproofed in a long time, so check its proof before buying to fire, 70 year old rifles can have a lot of things happen to it over the years,including fatigue in working parts , so a definite safety point to check.