ok so here it is,I have a jdm b18b all converted to obd1,but i want to put it in civic EK(ex)
so my questions is can i just buy a jumper harness and be ok and run my obd1 ecu as well.

How did you convert the motor to OBD1?? Did you switch the dizzy, remove the crank sensor and swap to obd1 injectors and any other related sensors?? This is a big waste of time and money. The B18b1 will drop right in a EK chassis and you can you the B18's sensors and the EK's harness with very little modification 97% of it plugs right in. To convert to OBD1 you buy an OBD2-OBD1 jumper harness, a OBD1 ecu and Hondata.

yeah,it was in a EG....n plus it didnt come with dizzy,and altenator or wire hanress....so i used all my obd1 stuff from my old ls(obd1)....so a jumper harness and i should be good?
is there any wire mods i have to do?

Wow you have a mix and match motor and wiring set up. Treat it like a B18a at this point. Get a obd1 dizzy and b18a harness.

Use your stock wiring harness.

Yea you can also use you stock harness. But some of the sensors will be different due to the motor having obd1 sensors on it. You will not pass emission in obd1 form as well. The best thing to do at this point is to put back on all thr obd2 sensors, get a obd2 dizzy and bolt it in the car. As for ECU choices if you want to tune the use an obd1 ecu and a jumper harness and chip with Hondata as i said before. Or get a obd2 P75 ecu this is street legal and emission friendly. I have done is swap not long ago about 6 months or so to my owe car. Hasport really helped me out alot with all my questions.