Pic resources below as well...

Okay. as far as wiring harnesses (MANUAL ONLY) go for civics and integras, they are one and the same. for 92-95 civics and 92-01 integras. dx/lx non vtecs are comparable to an LS. Ex vtec are comparable to gsr (b17 or b18c1)

obd2 wiring harnesses in integras are backwards compatible with obd1. the obd1 ecu simply ignores the extra sensors that are there (it has no idea they exists). obd1 harnesses are nearly backwards compatible. you will need an obd2a/b (depending on the year of the integra) to obd1 jumper harness and obd1 ecu.

when swapping an integra (any year from 92-01) manual motor into a 92-95 civic (lx, dx, or ex) it is plug and play. if it is a 99 b18b1 it will work in a 93ex. if it is a 92 b18a1 in a 95dx, it will work. If you have a 96-2000 civic, you have no choice (without cutting or swapping an integra dash harness) but to use the civic 1 piece harness. it will plug and play, but with obd1 motors, you will need an obd1 jumper harness and an obd1 ecu.

there is never a need to cut a harness. if your LS motor has no harness, use the one from the civic. ALL SENSORS WILL PLUG THE SAME. there may be differences in the alternator/distributor depending on year of the integra motor.

cutting harnesses are unreliable. users above mentioned cutting harnesses. they are only a good connection if soldered. THE ECU (if obd1 ecu to obd2 motor) will ignore all extra sensors.

Injectors are interchangeable (as far as the injectors them selves obd1 and obd2 are not directly interchangeable)
Alternators are Close to interchangeable. there are slight belt length differences.

For specific instances of Injector/Alternator/distributor mixes and matches. all instances will not require cutting of the harness.

95 ex chassis using a 98 b18b1 WITH NO HARNESS. you will need an alternator from a 92-95 integra (b18b1 or a1) and a distributor from a 92-95 integra (b18b1 or a1). you will utilize civic injectors, civic wire harness (you will not plug up your vtec hence the extra green plug near the dizzy)
97 hx using a 2000 b18b1 can not use the integra 2 piece hanress. you must utilize the civic harness (without cutting). you can still use either civic or integra injectors (both are obd2) and and alternator from 2000 LS will plug into 97hx civic harness (both are obd2)
IF you have a 99-2000 civic, there will still be a slight problem with utilizing your SOHC harness. the tachometer will no longer work, if you choose to depin the dizzy plug and rewire the distributor to fit. the tach signal is interpreted by the crank flux sensor and signal is sent to the tach from the ecu.

GSR and B16 swaps (into 92-95) require the vtec pressure switch and vtec signal.(you will need a gsr integra 2 piece harness and matching dizzy/injectors/alternator) your speed sensor must be connected as well as your car has to be at operating temperature for the vtec to actuate. ALL 92 civics are wired for Vtec on the firewall harness.

96-00 civic will require obd2 injectors/alternator/dizzy and a 96-98 ex wiring harness. if your motor is obd1 you will also need an obd1 jumper harness and obd1 ecu. (there is no crank flux sensor and no second o2 sensor on obd1 motors)