Ok for engine harness you can use 99-01 gsr, 99-00 civic si. You can use a integra non-vtec harnness but it will have to be modified. For an ecu: It all depends on what you plan on doing. Street legal? Pass smog? Track vehicle? If you need it to pass smog then use a obd2b ecu from a 99-01 teg or 99-00 civic si. If it doesnt need to pass smog/emissions/inspections then you can use p28(will need to be reburned for dohc), p30, p61, p72. If you do decide to go wityh an obd1 ecu then a obd2b to obd1 jumper harnees will be needed. YEs the p2t ecu is from the 99-00 civic si. Yes it will work.