The EFI was the same from the start in 75 through 83 with very little changes. It was a Bosh design built by/for Nissan.

I don't think they even used a O2 sensor till 82? Only sensors are water temp some have air temp. If you add in restors in the water temp circut you can change the fuel mixture a little or enough to drowned the engine. Hence the custom fuel enrichment for the turbo.

The 260 and 280 also have longer frame rails under the floor.

What else do you care to know. 

I spent years working on the early Z's up to 83. After they went to the new body with the V6 I kind of faded away.

This is the LAST one I restored, it is a 78.