We did it on my brothers SS. Got the whole rear sub frame drop out for around $1200 iirc. Just know that that diff is EXTREMELY heavy compared to ours. You will be dropping to a 3.23(auto) or 3.73(manual) rear end gear from our stock 3.91.
Really don't recommend the swap for a z28. Is this for drag racing? I've seen aftermarket ford 9 inch set ups that drop into our subframe that would probably hold up better
If you do it though you will need a driveshaft and should do the sub frame bushings while its out of the car.
here's a link to the swap another member did on an SS. parts list should be similar.
https://www.camaro5.com/forums/showthread.php?t=473478