I picked up an 83 Trek 620 in November in the same Pewter/light blue color scheme. It is a beautiful bike and I can't wait to get it out on the road. Mine is also in very good condition, although it has had quite a few components upgraded--700C wheelset, Shimano 600 RD and indexed downtube shifters, short stem, aero brake levers.

I don't know much about the touch-up paint, but if you find out anything, please PM me.