Update for the Mazda fuel pump wiring, run new wire and reley from the run section of the ignition switch and connect to the wire going to the fuel pump and everything will work just fine. I have been running mine since last August 2010, it is very fine.

I've never done this on a car of this vintage, but I'd guess that you can safely remove all the injection-related circuitry, unless it also connects to something unrelated. But these cars didn't have true engine management like modern cars do, so I doubt there will be any issues.

Moved this to our technical articles area.