Boss re-barrelled a lot of their guns with dovetail barrels. I have seen it done on guns by most London makers except Purdey. Some were dovetailed befor chopper lumping became the norm (like steel barrelled Holland & Holland dated 1893 I have.

I would expect to see perhaps a 10% price differential if the seller will ware it. Many will not because they can sell to someone who doen not know or care what chopper lump barrels are - they just see a nice gun with new barrels by the maker.