First thing to note, any cleaning could ruin the original blueing (that's if - there was any to begin with)
If you care about value its best to leave it be and ocassionally coat blade with some gun oil.
More importantly, never leave a carbon blade inside its sheath during storage.
However, if that's not a matter with you; you could sand down the blade to remove deep rusting/imperfections. And then polish it up with fine abrasive metal polish and "gun blue/cold blue" the bare carbon steel blade. If your's is a third pattern zinc handle F/S, you would find that the handle has been coated in a black paint. If its all worn out you could use a chemical paint stripper and wipe of all traces of the original paint and then mask off the guard/main blade before you apply a good coat of durable matt/satin finish metal/enamel spray paint. Best of luck.
Krizzard, out
"...Whoever kills with the sword must be killed by the sword... "
- The New Testament, Revelation 13:10