Another way to think about it is that wood can be changed either if you do not think it will effect the value of the gun, or you don't care about collectors value. As Ray said a Sercey is attractive because you can use it and not worry about ruining your investment, also you can get the stock bend, shortened, lengthed or even restocked so that it fits you.

I am not saying here take a hack saw to cherry Purdey or Boss, but if you are looking at a working double rifle, just like a working double shotgun, don't get too stuck on whether the rifle "as is" fits you or not. The stock can be changed usually for much less expense than rechambering; reregulating etc. Buy the rifle from the action forward unless the measurements are really off and you are looking at a total restocking job (which gets pricey). Get your measurements from a good smith or gunfitter and then shop arround. No need to not buy a rifle you really like because it was made for a lefty, or someone with really different measurements, or to get struck with a caliber or action you don't like because the wood fits you better.

No all this applies only when you are comfortable with changing the stock, if not I AM NOT saying ruin a collectors piece. But if you are afraid of modifying the stock for fear of value, would you feel comfortable hunting with the rifle?