First off, the prototypes of these two cars are from different eras: your CSX hopper is a model of a 100 or 125 ton car, and would be suitable if you're modelling a present-day railroad. The L&N car is a model of a 50 or 55 ton hopper: the first steel ones were introduced early in the 20th century, and were used as late as the 1960s or so. As for the "fit" on the track, unless the wheelsets are one-piece, you should be able to re-gauge the wheels by sliding them outward on the axle until they line up properly with the rails. A NMRA wheel and track gauge is handy for this, and many other, uses.
Wayne