Wow, I see the dilema. If it were me, I`d probably keep the Expedition frame and put on whatever components it took to keep me from longing too much for modern conveniences, then go out and give it some tender loving abuse. Beautiful lugged frame, aluminum quill stem, gum hooded non-aero levers- tasty...
There`s definitely something to be said for keeping it pristine, though. I don`t know what kind of money it would fetch right now, but I`m sure you`re right about the value dropping considerably when that original paint gets scratched, abraded, and faded, even if most of the stock components are stashed safely in a cardboard coffin somewhere. Either way makes sense depending on how you look at it, so I guess just follow your heart. And thanks for posting the porn