I'm not very knowledgeable in classic or vintage bikes but I'm going to go check out a Mikkelsen (Bay area framebuilder: http://www.mikkelsenframes.com/). I've talked with the owner here is what I've learned:
1. Been in storage for a very long time.
2. No rust on the frame, but a few chips
3. Tires should be replaced
Mikkelsen lugged Columbus 62 cm (says it's at least SL and the bike weighs 23lbs.)
old Campy record components (crankset, rear derailluer, shifters)
Dura-Ace front derailluer
New brake hoods and new tires and probably re-cabling.
My perspective: I'm looking to make this my first geared bike in years (I'm riding a fixed right now) and I want something dependable and fun-to-ride. Not looking for a collector's piece.
What do you guys think? What should I look for specifically?