if i were to build a power line/big game plot/clear cut rifle, one that would be shot off a shooting house window sill or such, i'd start with my macmillan bench rest stock for a long-action remington 700. it has been sitting around for years, waiting for me to put together a rifle. it is used, and was a gift.
that means a remington 700 long action. so, on to the chambering: if a belted magnum factory round, then probably 7mm remington magnum; if standard .462 case size, then .270 winchester.
if wildcat, then 6.5mm-'06 improved.