I believe sheldon brown offers a chart of what bearing sizes to get, that or harris cyclery, I dont remember for sure.
If you are re-assembling a bike, a few things to keep in mind:
*grease EVERYTHING. I like to use phil grease, but only because it's what I've always used, I'm sure park grease is good. A few things I run into people overlooking ALL THE TIME when greasing are seatposts, pedals and cranks/bottom bracket spindles.
*if the hubs or bottom bracket are loose ball, go to town and rebuild those while you are at it. While you are up to your elbows in grease, might as well have a grand old time of things.

Thats all I've got for now.