Rule number 1: Always use your original harness from the car and add more wires later. Unless you have an eg, the integra harness will virtually plug and play with the eg especially if you have an integras GSR harness.
You are lucky that the head is obd1 therefore, I'm assuming that the injector wires are obd1 and distributor is obd1 since your vehicle is obd1 already. This means its plug and play.
My suggestion: Take out your original harness from the civic. Start plugging it into the sensors on the gsr motor while the motor is out of the car. At this time you can start adding wires and seeing what sensors need to be plugged up.
If you have a JDM gsr engine harness, keep it for sensor parts! You cannot reuse it for your left hand drive vehicle.
If you have the USDM gsr engine harness that came with the motor, then KEEP that and replace it with your original civic harness. Just use it and plug and play
*In my opinion, the IABS is a great function! I wouldn't open it up and remove the middle plate for any reason if you plan on using it. Its function was to give you more torque in the low end, then opens up in the high end because we all know people don't drive around engaging in vtec all day.
You don't need a tuner to disable the IABs. All you have to do is just unplug it and it will remain open. Especially if you removed the middle plate for it. There will not be a check engine light at all!
As for the knock sensor and oil switch, they are all the same. The only wires you would have to wire up is the knock sensor, vtec, vtec pressure switch, IAB, and maybe do the IACV conversion. I'm not really sure for EG civics but for EK the IAB conversion is a must!