1. Electric pickup can be used with the Electric Speedos on the Market (~AU$380). Or you can pay $10 at the wreckers, and get a mechanical speedo drive from a skyline, and use a S2 Bluebird speedo cable (Take your 1200 cable to the wreckers, you'll find the bluebird one has the same ends, but is a foot longer)

2. Tacho, you have 2 choices,
a. use the tacho out from the standard ECU (Yellow with red trace (pin7 on ECU))
b. Splice the 1200 tacho inline with the 12V feed to the coils. The 1200 Tacho is an inductive loop, and the only thing that can fail is the old spade connectors. You might want to replace them on the tacho to ensure reliable connections. If the tacho connection fall apart, you'll lose ignition.

Chris