Based on your photos, it looks original. Don't know anything about the holster or lanyard, but for an all-matching all-original Navy-stamped Victory in that condition $650 is an excellent price, so any value of the accessories as indicated by jpage above is frosting on the cake.

As for the back story, the gun looks too good to have seen much action, particularly the lack of dings on the stocks. The holster looks significantly more used than the gun. If it comes from a vet's family, it is still more likely that he picked the gun up some time after the war, though maybe the holster was his.