Difficult to give any idea of value without 'hands-on'. Apart from that I am way out of touch with values, even here in the UK. Generally this gun has some attributes that would lower the value quite drastically (from a buyer's viewpoint). Firstly the mis-naming. As Tim said probably an engraving error. Then the Black Powder proof. Then the barrel pits. Its unusual to find an unmolested gun of this age without pits but prior to thickness measurement (or a very experienced visual) who is to know if the tubes will clean up and still leave you sufficient wall ?. I know you do not have Proof laws as such across there but the visual/measurement aspect must be similiar.In my limited experience lots of guns of this vintage have relatively thick walls and may gauge around .710". With luck that leaves a bit of room for clean up.
If I had to guess I would be looking at the low 100's of dollars $Can or US. Generally I would never pay more than I could afford to lose if it turned out to be a p.o.s.
Sorry, I know none of that is any real help.
