As far as I know on a Z/28 the front and the rear is different in rim size. Tires are the same, but the rims are different. Front is 19"x11" (48.26 cm x 27.94 cm) rear is 19"x11.5" (48.26 cm x 29.21 cm) and they can not interchange front to rear or rear to front. I've had first hand experience with this at a tire shop. Where they mistaken and installed rear to the front. Bunch of "Scheisse Kopf"
https://www.camaro5.com/forums/showthread.php?t=369676
This old thread might help. Good luck.
Besides why would you want to change out the Z/28 wheels for ZL1. Original Z rims are hard to get.