If its an 88-91 dohc zc.
pm7=ecu made for the motor, right fuel curves and maps, speed capped at 112mph.
pg7=ecu from an (88-89?) integra, similar fuel curves and maps, works great, some say it runs rich.
pm6=ecu from a 88-91 crx/civic si, runs motor ok but with more conservative fuel maps and lower rev limit.