That bike probably takes 27" wheels - should be reasonably easy and cheap to find a used 27" rear w/ 5/6 speed freewheel, an old Suntour or Shimano derailer, and a set of old clamp-on shifters. Maybe even post a wanted ad in C&V classifieds here on Bike Forums. Or if you have a bike co-op in Richmond (seems logical enough, from what I remember of the town), or a good sized LBS that does fixed conversions, those would probably be good sources too.

Personally, I would just commute fixed for the time being and use this an excuse to buy another bike. Or throw a bigger freewheel on the flop to deal with the hills, and again, use it as an excuse to buy another bike.