Ahh, you're installing the Painless Wiring fuse box only?...after straining my eyes to read the Datsun wiring diagrams, I changed my mind and ripped out the whole dang thing and installed the 18-circuit harness with fusebox.
Even now when I have wiring trouble, I can just look at the wire and identify it very easily because each is colored, labeled/numbered, and divided into sections. If it's not too late you may want to do this.
Owen