Larry,
On my original Z28, original battery cables (late 09C build), both the large battery cables are black, and the smaller attached cables are black. The only *red* item for the POS cable is the side terminal itself... (see photo).
I'm also attaching a photo of original cables from the Oregon 'barn find' Z28, discussed on TC a couple of years ago. Both of these cars are late build cars, one from Norwood and one from LA...
Gary