IMO, very much on the high side.
$6500 is approaching Farq. and Alex Henry money, and there really is no comparison.
Also looks to have been fully refinished, so a few notches below the top as a collector piece.
I don't know how many Martinis Westley Richards built, but period catalogs show them to have been at the lower end of their price range.
Would be a fun rifle though and I do love Martinis.