I have done a few of these.
You can use stock C4 auto driveshaft (no custom driveshaft needed) also use stock C4 automatic C-beam and stock C4 dipstick.
Yeap PI has both measurements for 4L60 and 4L80 Torque Converters thanks to yours truely
Also exhaust will need to be modified to fit around auto trans.
How much horsepower you making in that Z?
Pete