The springs are definitely the later ones with the smaller diameter top. FK do two spring caps, up to 07/93 and after 08/93, so will order the latter.
Are you thinking of replacing the shocks as well, might be worth thinking about.
I expect I will at some point, or may even get a decent set of coilovers. For the moment however I'm being cheap and it will just be the springs, with only a 20mm drop hopefully it shouldn't ride to bad on the standard shocks.