Sounds like it is a Campy NR or SR (vintage) crankset/BB. Not sure why you would want to change the crankset, as those are nice. The Park tool for that should be this

http://www.parktool.com/product/cran...t-wrench-hcw-4

Take a look at Sheldon Brown's page on bottom brackets, and the tool you can easily make for removing a tight fixed cup. I take mine out all the time (yearly) for cleaning, but mine are English threaded and come out pretty easily. On a tight one like yours, I would do as advised and leave it alone unless you absolutely have to get it out. And then I would spray the threading with PB Blaster or the like, and let it soak in for a few days.

Also note that Campy uses an ISO taper on their spindles vs. JIS on Shimano and most others, so if you did replace the crankset, you would also want to use a suitable bottom bracket for the particular crankset.