All of the above.

For an illustration of the freehub bodies, check here

And for parts, well it's true that it is hard to find. Most Campy distributors will stock 8-speed cassettes however, so grab a few while you can. The only other critical part might be the rear derailleur. You can always overhaul the shifters. Can you use 10-9 speed front derailleur and chainrings on 8 speed?