I am attempting to drag a 1980 Schwinn Collegiate 3 into the next millenium. I've laced some aluminum rims to the old hubs, slapped on a Shimano sidepull brake and now I'm interested in going 3 piece. I've been inside the BB to repack the bearings, so I've got a basic understanding of what's in there. What would you all recommend for converting to 3 piece and what cranks/BB/chainring would you use?  I did a search of the forums and will use the truvativ American-to-English adapter. I'd like to use a Shimano BB, but my skills are exceeded with the task of choosing lengths and cranks to recreated the chainline. 
Thanks for your responses. It's been a great project so far. It's lighter with every change of equipment, and Holy Cow! it actually stops now.