Welcome, SMB_fan.
First, thanks for making me feel old by talking about your Dad playing ... it had not yet occured to me that I too could have had a kid who is 15 now ... thanks ...

Be sure to check out wilef's Mario Bros (And his brother's DK3) build:
http://mariobrosarcade.blogspot.com/There is a thread somewhere here in PA, but I am too tired to look for it right now. He has already faced much of what you are looking at, with excellent results - learn from him, young paduan. There is another Nintendo replica cab in PA as well, but I haven't had enough coffee yet. You should definitely search for it.
I have never seen just a unisystem CPO (and they're not the most attractive things ever), but controls panels pop up all the time on eBay -- check there before buying any sticks or buttons. There is someone making repro marquees -- search these forums and you'll find it -- I have one and it is great. The VS sideart is pretty boring, but does show up on eBay and RGVAC from time to time.
Cheers