Most of Campy's crank also have one bolt that goes into the back side of the crankarm, to there's more the compatiblity issue than just the BCD. The chainring must be made such that the right side of the big ring has the proper dimensions, and the chairning would have a countersunk hole on the left side. Other brands make totally compatible chainrings, just for Campy crankarms.

I'd ask the OP why he changed the cassette so soon? I expect 12-15,000 miles from a cassette. If you put a new chain on an got chain skip, then you left the last chain in use for too long.