You need conversion cables, ebrake splash shield, all the ebrake parts (don't lose any haha).

Redrill the rotors or Circuit Sports Z32 Rear Brake Rotors

Online Nissan 300ZX service manual
^helpful for the ebrake guts assembly if you're not good with drum style brakes.

Run the ebrake cables through the ovals in the LCA and put them in to the T where the cable from the handle splits to each wheel. You'll have to mount the cables to the car so they don't hit the driveshaft but it's pretty easy.