If the 8 speed wheels will fit between the dropouts you should be fine, but 6 speed may be 126 spacing and you will need 135.
8 speed campag has the same spacing between the cogs as 5, 6 and 7 speed.
A old Nuovo Record rear mech has enough travel for a 7 speed block, but I think for 8 speed you may need a later rear mech from the c-record/chorus era
If the 8 speed wheels will fit between the dropouts you should be fine, but 6 speed may be 126 spacing and you will need 135.
8 speed campag has the same spacing between the cogs as 5, 6 and 7 speed.
A old Nuovo Record rear mech has enough travel for a 7 speed block, but I think for 8 speed you may need a later rear mech from the c-record/chorus era