if you just want to lower it an inch or so, improve the handling and do a few events, there's no need for coilovers.

having said that, aftermarket lowered coils for Datsuns are rubbish! If you had a Holden or Falcon they put a bit of effort into making coils that work, but for old Datsuns etc they're just whatever they already had that fits. Eg - Kings springs lowered stanza coil is the exact same part they list for a standard 1200 coil!

Go and get a set of Gemini coils from a wrecker and cut them. leave the variable rate part on there and you get fantastic ride quality and a big handling improvement.