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I would highly recommend you get some of these.  This kit comes ready to run and is prototypically correct.  The lettering is almost  perfect.  Mine are numbered #835031 which puts it in the #835000-835154 HC-13 class, and #837530 which puts it in the #837530-837554 HC-20 class.  If you get an undecorated one, the road number needs to fall into either of those ranges to be prototypically correct for the B&O.

Note that some cylindirical hoppers have 6 doors on the bottom and some have 3.  The B&O had both.  I know the C&O had the 3 bays, but am uncertain about the 6's.

Below is a Dean Heacock pic of a cylindrical hopper.

                                                              Dean Heacock photo

Below is a pic of my Atlas cylindrical hoppers.  I didn't do much more than weather the wheels, trucks, and a light coat of weathering along the bottom 1/4 of the car.  I wanted my Chessie one to look clean like the photo above.  The B&O one on the other hand should be faded.

This kit is so good right out of the box that you could run it without any improvements.  The only fault I have seen with the Chessie painted one, (I did not change this on my car), is the end platforms (area behind the ladders) are yellow not blue.  An easy wat to hide this is to fill the area with dirt.  These platforms collected dirt like they were dust pans.  Just put some scenery glue in there and sprinkle in some dirt.  It would be a very convincing addition.  Out of the box this kit is 95% or so accurate.

Notice that to the left of the Ches-C logo on the real car above is the famous Chessie bowling ball safety logo, this was not on all cars, so I can not say if it was ever on the cylindrical hopper below.  If it was, then a simple addition of a decal would make this hopper correct.