My take from the photo and description. Linsley = BV3, About a "B" grade SLE = OQ3, current condition is something like "significant use" to heavy use but no abuse" = CC3.5. BV3-OQ3-CC3.5 = $4800 + whatever premium you care to pay for 16 bore. It would appear to have very "shootable dimensions," depending ou yoour dimensions. The engraving seems a notch or two above a flatback back action gun; you might give it a bit of premium for that. The wood looks O.K., but not a higher grade. The forearm checkering looks a tad substandard.
Linsley has a following, but this looks to be a typical Birmingham product. Note that it didn't sell for $8K!!