I looked at this as a customer asked if we could do this while we were
swapping the turbo engine from an 83 ZX into his 76 280Z. The rack mounting
points are different and it would require a major hack/fabricate of the
front cross member to allow the rack to sit in the car at the right angle
to attach the steering shaft as the power rack is really thick where the
steering shaft connects. I doubt any power rack would be an easy fit. He
didn't want to pay what it would cost for this and I doubt anyone else
would either? These cars don't steer that heavy IMHO to need pwr steering
anyway.

If you have to have pwr steering, get a ZX that already has it. The early
ZX's had recirc ball steering while the 83's had a power rack which works
much better.

Learn to do handbrake turns.

Just kidding.  In my experience using radial tires with
compliant sidewalls makes a big difference.  
Yes, my first Z came with bias ply tires.

My '77 has factory PS. It should'nt be that hard to put into a '74 - at
worst you just swap out the front suspension (4 or 5 hours tops).

Even with 3 point turns, it makes absolutely no sense in putting power
steering on a z.

The steering is too light as it is.  Get another car, like a 280zx,
which has power steering if it is necessary.

You are talking about thousands of dollars invested (at least in labor
at the fabrication).