Wow, thanks guys, that's a lot to work with. Here's what I'm thinking so far:
Some of you guys kinda missed my point with the 50cc thing. Sure I'm well aware I can spend minimal money and get a bigger kit, and in fact I've ridden many kitted bikes, but I'm building a 50 because I want to build a fast 50, not a fast 65 or 70 or 80 or anything more insane. All the same, duly noted.
And since EVERYONE had something to say about cranks, here's my two cents on it. I don't think anyone's a "retard" for running a stock crank, but the valid point was made: I've seen performance and stock cranks side by side, and making my judgements off of that, I'd feel better running a needle bearing with space for oiling. I've never had anything catastrophically fail on me, but I have worn out stock cranks just on normal riding on stock bikes. The small end doesn't hold up, and anyone who says otherwise must think that loud metallic knock they're hearing is normal. It isn't.
However, I am convinced I ought to get a phgb tunable carb. Maybe not necessary on a 50, but it's certainly not going to hurt, and being able to tune the whole range of throttle sounds appealing since this is a commuter bike, I won't be at WOT the whole way or anything near it.
And to answer everyone's question, yes I already have new tired. Too dumb to blow an old tire or wreck because you thought bald tires were good enough for you. Same with brakes and cables, new all the way, this hobby's dangerous enough.
Thanks everyone, I'll update anyone that cares when I start my build, more advice and experience is always appreciated!
@ andrewhed: I loved your idea for a setup, but that'll be my next build. I'm determined to build a passable 50cc first.