Do you have any close-ups of the engraving on the sides of the receiver?
In good used condition, it is rare for these guns to bring more than $800 or so. The Westly-Richards droplock versions do go up to $2500-$3500 (I have only seen two and couldn't afford them at the time).
With cut barrels, I would think the gun would go for $300-$500.
The sad thing is that even if you had the barrels redone, the gun wouldn't bring what it cost for the barrel work.
If you were interested in selling, I would be interested as collecting these guns has become an interest of mine.