RE: I think I just found my Halloween buck!
I'm late to this, but I'll still offer my opinion. Honestly I don't think there is any accepted protocol in a situation like this and the ethics police and take a flying leap. (Which, fortunately I don;t think any have really showed up here anyways).
I'd guess that this is very likely the buck you shot. Bummer you didn't find him in a timely fashion, but getting closure helps a lot. Your decidion from here on out to do whatever you wish as far as tagging and the rack & stuff, can only be made by you. Don't get yourself in too much an ethical dilemma as like I said htis situation doesn't realy have a right or wrong answer.