Regarding the wheel, the last thing I would mismatch is the spoke count. Some will and have without negative effects, but you can also just buy an old wheel with the correct rim and swap over the rim.

Also, if you really have 7-sprockets on that wheel, possibly it's really a Campy freewheel, not a Campy cassette. If so, the freewheel is a valuable part. You could Ebay it and then do something different.