If you are putting on a larger throttle and ported intake, do the turbo AFM upgrade. Buy a Air Flow Meter from a 280zx turbo. Take out the inside electric components. Put the AFM components from a non-turbo AFM inside the housing of the Turbo Meter. Then you'll have to adjust it untill your car runs at the correct richness. This will open up the bottleneck in your intake. Of course, use a cone K&N air filter on the front of your induction tube.

Shave the head slightly on your Z, and advance the cam sprocket one point to correct the slack in the timing chain. Raising the compression helps with torque as well as makes way for a performance cam and new followers.