This brake-line "splitter" in the picture (which is sitting on top of the large vacuum hose) is named the "Warning Light Switch". It has the same number of lines as the stock Datsun 1200 switch:
Brake line pressure differential Warning Light SwitchThere are two inputs (front and rear from master cylinder). And three output (two for each front brake, and one for the rear brakes. The rear axle has a simple line splitter bolted to it to go to each rear brake. The electrical connector goes to the dash light.
It doesn't effect brake bias (it's not a proportioning valve) so you could use the Datsun 1200 one. But like Chris says, it might be easier to use the one that matches the cylinder. At least the input lines will match up nice.