Hi,
The revolver was made in July of 1863. The cone style is the correct front sight for the serial number of the revolver. There is no price degradation for the “mismatched cylinder” because the cylinder probably is not a replacement. Remington stamped the serial number in three places on the revolver: under the barrel, on the left grip strap and on the trigger guard tab. Remington did not normally mark their cylinders. When a number is found on the cylinder it usually means that some hand fitting was required for the revolver to work properly. It was marked to be able to match it to the other parts during final assembly.
As far as price goes we don’t quote prices because it is almost impossible to properly value a gun without examining it in person.
Hope this helps,
Bill