I would walk away from it, put your $400 aside, add to it when you can, save until you can get a nice Brit boxlock double.
I know the name PARKER carries some kind of aura for many double guys, and some will jump in here, but it certainly can't make this bottom model worthwhile. The missing chunk of wood, the barrels look rusty onthe outside, probably worse on the inside. As presented, it's junk and I can't even see the whole gun.
Don't make the mistake of buying the name, save your money andput it towards a worthwhile double you won't have to put MORE money into to make it serviceable.
Please do yourself a favor and forget this hunk of nothing.