But the site, to which you link, says the Campy 8 sp and the 'standard' 7-sp freewheel (isn't that what Fender is talking about) are both spaced 5.0 mm. Seems to me it will work. But what do I know.
Completely off topic, but I saw you have a 1993 Basso Gap. I have a chance to buy a 1993 Basso Gap (Athena). The bike is in excellent shape - well maintained, clean frame with no defects, and all original components. Is $500 a fair price?