I've been looking to do a similar build from a late 80's or so frame set. My plan is to use a SunTour Superbe/Cyclone group I've got around here, drop some bar-end shifters on some bars from Velo-Orange (type to be determined). I'd end up with a 52/42 up front, 14-28 in back running on a Cyclone GT rear derailleur. Perhaps throw on a sprung brooks saddle (or maybe not depending on the range of weather to be encountered in your case) for added throw back look.