As you are upgrading the brake lines to SS ones, I'd also go for upgraded discs and pads and of course a decent fluid, such as Motul RBF600.
I'd look at suspension tweaks too, the best thing I did to my Z was change the ARBs to Eibach ARBs + decent drop links, add stiffer suspension springs and get a proper alignment setup done (at Abbey Motorsport). Obviously good tyres too. This massively improves the handling of the car and how you can utilise the extra power from a remap etc.
I personally wouldn't bother with the damper, or the pulleys and I'd leave the clutch until it actually needs replacing. If I was going FI then I'd upgrade the clutch first.
If you're looking for the best gains then the stock air box + filter panel/decats/upgraded exhaust seems to be the best proven method and in your case a spacer on the earlier models. A few people go for headers but they are tricky to fit and quite expensive for relatively little gains, imo.