Just got a Silvia s12 for £70!

[30psi]

For springs, cheapest is cut them, second is buy some chassis dynamic or AVO springs (pm Adz-s12, he has a set going spare), more expensive is to convert the fronts to coilovers using rally design bits or most expensive is to use S13 coilovers. The rear is spring/shock seperate so its best just to use a normal lowering spring there.

Performance pads - Mintex or Ferodo. I found budget 'Apec' pads work v well.

The engine is a single cam CA18ET (not DET). Anyway oil use grades like 10/40 and thicker and best to be at least semi synthetic. Magnatec upwards really. I use Castrol RS, Mobil 1 or Silkolene in 10/50 ish grades.

HT leads - They are some around but they are expensive. I think Magnecor make a set. I used Mallory leads which are 8mm and cheap but you make them up yourself.

The order you have for mods seems reasonable enough to me.

There's loads of sites for the S12. In addition try the tech s12 section of www.sxoc.co.uk. The US has www.club-s12.org/board

For a short shifter just find one that is compatable with the S13 200sx, for about £40.