The main issue for shifting is the differences in spacing between the rear sprockets.
I think campagnolo 7 and 8 speed have the same spacing as shimano 7 speed,
so if you can find some 7 speed shimano MTB shifters (thumbies, stis etc) they should work
with a campagnolo cassette and deraileur.
Might be a bit more complicated for the front derailleur though - probably easier to use
a non-indexed shifter than to break your balls trying to match up an MTB shifter with a
For wisdom on this kind of thing, see this:http://sheldonbrown.com/speeds.html
Plus, if it's really a 7 speed campag ergopower set up, it might be quite rare and interesting to collectors (some people deny it exists at all because it was only made for a short run before they started with 8 speed), especially
if in good working order.
If you sold it, you might get enough funds to re-equip the bike with some sturdy modern shimano MTB stuff.