There is not much to wire up on a idi, just fuel shut off solenoid, cold advanced, fast idle, glow plugs and temp/pressure sensors. A ignition wire would need ran to the fuel shut off solenoid, this is the front spade on the drivers side of the injection pump. Front intake side of the passenger side head is a sensor to control cold advanced and fast idle, this will get a split in the ignition wire and cold advance is the rear spade on the driver side of the injection pump with fast idle being the thingy by throttle arm. Coolant temp is on a bridge in the block by driverside front of head and ignore the one on the outside of the head. Oil pressure is a can that sticks up on passenger side behind the head, you should have a sensor as aposed to a switch. That means you can mod the idiot gauge to work some, pull the cluster and behind that gauge is a resistor that just needs a wire jumped accrost it. As for the glow plugs you can get something like this with matching plugs, hook it to a starter relay with a wire hooked to a push button on dash. I think this is for 6v glow plugs and can give issues like that, someone might clime in with more on that.
https://classicdieseldesigns.com/products/non-turbo-location-glowplug-replacement-harness
