Z chains don't last very long - they tend to stretch out pretty quickly. I personally like the Sram pc-1 which is like $10-15 and resists street crud better than a higher end chain. In any case, go for a 1/8" chain with your current chainring and you should be fine (and it'll be a little more forgiving / quiet if your chainline is a little bit off).

All modern chains are 1/2" pitch; you'll occasionally see an old inch-pitch drivechain on a vintage track bike but there's not much fear of accidentally buying one.