I too removed nearly all of the emissions and "extra" items on my 280. EGR, Cold Start Valve, BCCD, Carbon Canister, PCV system (filters instead), AAR, and also the water temp sensor. I have alot of extra wiring now, but I planned on redoing my harness soon so I just tied them out of the way. I found a good thread on hybridz that listed the majority of the items:
Carbon Canister (surrounding area will smell like gas after you shut it down hot, gas fumes in the engine compartment). No performance benefit.
EGR Vacuum line - this will shut off the EGR permanently. You can also remove the EGR entirely, but you must make a block-off plate. No performance benefit.
Injector cooling fan - you probably did this already. No performance benefit.
TPS - throttle position switch. May cause idling or WOT issues.
AAR - you will have a slow idle when cold, may stall out. No performance benefit.
Idle speed adjustment - see above. No performance benefit.
PCV system - underhood will smell like blowby if you have any. No performance benefit.
BCDD lines - actually removing unit may require taking manifold off and making block off plate, not sure. No performance benefit.
Ported vacuum system, including TVV and all lines. Move distributor line to manifold vacuum. Adjust base timing accordingly, remove 12V advance if desired. No real performance benefit.
Coolant lines that run to the AAR and throttle body.
Cold Start Valve - May cause extremely cold starting problems. No performance benefit.
I do recall reading that the stock Z efi system is designed to be used with a rising rate fuel pressure regulator. A drop in vacuum (open throttle) adds more fuel pressure (more fuel) and Higher vaccum (closed throttle) reduces fuel pressure (less fuel). But I am swapping to a new fuel rail with a new regulator so I am not worried.
During my research, I also got the vibe that it was sacrilegious to remove anything the Datsun engineers installed. Even if I sell a Z part locally and take to the buyer, 50% of the time they ask me why I removed what I did. But it didn't stop me, nor should it stop you if thats what you want to do to your car. If we all followed the FSM, none of our builds would be interesting 🙂
But take what I did with a grain of salt as my Z has only been around the block twice 😄