Thanks. I got so much help from this board and its members it's not even funny.
I'm actually starting my next project this weekend- some strange person I met on the internet (sounds creepy, I know) is getting rid of a "Two Tigers" Machine (the Tron conversion kit w/2 optical spinners), and is just giving it to me for free, so I'm pretty stoked. I'm thinking of giving it a tasteful Mameing, while still keeping its original look and original equipment. It's got a busted monitor, but aside from that, the controls/coin mechs are still in okay shape. So yeah, I'm stoked about picking that up and having a project I can work on, and have some live progress posted here.
As for a trackball- I'd absolutely LOVE to put a trackball in, and maybe I will someday. I've been looking into hacking some old ones, and actually thought of building my own, but we'll see. It's a shame that all the trackballs I see are so bleedin' expensive, otherwise I wouldn't have thought twice.