you can scope a BC just fine. see my sig pic below. the weaver 93 and 82 rails work well. also check the FAQ's on centerfire rifles forums. halfway down the FAQ's there is a topic that shows what rails fit and a few pics of them and descriptions of yet a few more that work, including the NEF ultra scope rail.
keep in mind that you, more then not, are going to want a scope with more eye relief, about 5 inches or more. depending on what ranges you expect to shoot, you may want a scope that has bullet drop hash marks for 150 200 and 250 yards. and cheaply constructed scope may not hold up to the recoil of the BC, when you get up into the marlin levels the BC can deliver a solid thump and some scopes cant take it and loose zero.