I have a 1988 Trek 520. Bought new, still mostly stock. I believe the frame size is a 24" based on top tube lengths and the 1988 catalog on vintage-trek.
+ 27" wheels replaced with hand-build 700c MA-40's on Bullseye hubs ~1990
+ downtube SIS shifters replaced with Shimano bar-ends, then more recently with 7spd brifters (Tiagra) [still have the bar-ends]
+ new (well, the last time I rode it mid-09) 7spd freewheels
+ crankset (with Biopace chainrings) replaced with a Shimano M730 (vintage ~1990) and recently new middle Salsa chainring (non-ramped/pinned)
I never toured on the bike, and I have a ~1995 Topeak front low-rider for it, and a set of four unused ~1990 Mountainsmith panniers.
Bike was mostly used for commuting over a number of years, and probably doesn't have more than 2000 miles on it. There is a slight ding in the TT and some wear to the paint (never lend a bike to someone who'll carry it on a trunk rack with other bikes!).
For selling as a touring bike, should I leave the brifters on or put the bar-ends back? When I put the brifters on I'd replaced the handlebars with a wide (46cm?) Nitto bar, and I'd like to recover that for another bike, so I do need to unwrap the bars anyways.