Personally I would refinish it using files followed by backed sandpaper to sharpen the contours and make the surfaces flat and remove modern markings.The 19th century finishing was not perfect and tooling marks were left in places, but it was still much better than most of what you see today and they did not use buffing wheels to the extent that modern manufacturers do. Might want to install a higher dovetail sight at this point also which do appear on modified original percussion revolvers from time to time. Finish the brass to 320-400 grit and rub down with Scotchbright to get a soft finish. Following that a simple rust blue on the steel parts would be appropriate and historically correct. I would refinish the hammer and hand checker the top. I would follow this by re-hardening it using bone and wood charcoal color case hardening which I am setup to do, but that would be a minor point. Refinish the grips and go with an oil finish and just use it. It will get wear all on its own and look right, most of the aging I see people do looks overdone and not too believable.