I'd recommend a 4 way JS with three buttons. This gets you all the classics including Missile Command. I'd keep the game list down, say to 20 or less. Switching the JS between 4/8 is easy, but is hard to communicate to a young (or older) house guest. Also, with a CRT in the mix, heat is going to be an issue. Also keep an eye on the overall weight of the thing. Good luck with the build and I guess it's my turn to say it, take lots of pictures.